The Supermajority Machine 绝对多数机器
For 71 years the PRI held automatic supermajorities. The democratic transition produced genuine multiparty competition for 18 years (2000–2018). Morena reconstituted supermajority control in a single decade — winning 2/3 in both chambers by 2024. The chart tells the story: PRI collapse, fragmentation, reconsolidation. 71年间PRI自动拥有绝对多数。民主转型产生了18年的真正多党竞争（2000–2018）。Morena在十年内重建了绝对多数控制——到2024年赢得两院2/3。图表讲述了这个故事：PRI崩溃、碎片化、再整合。
Senate renewed entirely every 6 years (no staggered terms since 2018). 2024 result: Morena coalition 83/128 = 64.8%, just short of standalone 2/3 but achieved with allied votes.参议院每6年全面换届（2018年起不再交错换届）。2024年结果：Morena联盟83/128=64.8%，差一票2/3，但通过盟友投票实现。
The Laakso-Taagepera index measures fragmentation. Mexico peaked at ~4.7 in 2015, then collapsed to ~2.5 by 2024 as Morena absorbed satellite parties. The transition era was genuinely multiparty; the Morena era is structurally approaching a dominant-party system.Laakso-Taagepera指数衡量碎片化程度。墨西哥在2015年达到峰值约4.7，然后到2024年随着Morena吸收卫星党而降至约2.5。转型期是真正的多党制；Morena时代在结构上正趋向一党独大制。
| Power seat权力席位 | 2000 | 2006 | 2012 | 2018 | 2024 |
|---|
Mexico's 32 states elect governors on a rolling schedule (not all simultaneous). Party shown is the party at election. Governor party distribution: 2000: PRI 20, PAN 7, PRD 5. 2018: Morena 5, PAN 12, PRI 12, others 3. 2024: Morena + allies 24, PAN 3, PRI 2, MC 2, independent 1.墨西哥32州分批选举州长（不全同时）。显示当选时政党。州长政党分布：2000年：PRI 20、PAN 7、PRD 5。2018年：Morena 5、PAN 12、PRI 12、其他3。2024年：Morena及盟友24、PAN 3、PRI 2、MC 2、独立1。
Mexico's coalitions are structurally different from Brazil's墨西哥的联盟与巴西结构性不同
Morena coalition (2024)Morena联盟（2024）
376 / 500 = 75.2% in Cámara (2/3 = 334 needed). The coalition is not a negotiated Centrão-style bargain — it is a pre-electoral alliance where satellite parties (PVEM, PT) joined Morena before the election and received candidacies in exchange for loyalty. PVEM switched from PRI alliance to Morena alliance in 2021 — a pure survival calculation. The coalition functions as a single bloc under presidential direction.376/500=75.2%众议院（2/3需要334席）。联盟不是巴西Centrão式的谈判交易——而是选前联盟，卫星党（PVEM、PT）在选举前加入Morena并以候选权换取忠诚。PVEM于2021年从PRI联盟转投Morena——纯粹的生存算计。联盟在总统指示下作为单一集团运作。
Opposition bloc (2024)反对派集团（2024）
124 / 500 = 24.8%. Cannot block constitutional amendments alone (need 167). PRI has collapsed from 300+ seats in the 1990s to 35. PRD lost registration in 2024 — the party of Cuauhtémoc Cárdenas and the 1988 democratic movement ceased to exist. PAN is the only structured opposition force. MC remains independent but small.124/500=24.8%。无法独立阻止修宪（需要167席）。PRI从1990年代的300+席崩溃到35席。PRD在2024年失去注册资格——库奥特莫克·卡德纳斯和1988年民主运动的政党不复存在。PAN是唯一有组织的反对力量。MC保持独立但弱小。
The structural contrast with Brazil:与巴西的结构性对比： Brazil's Centrão holds 57–68% of Chamber seats in every election and forces every president to negotiate. Mexico has no Centrão — it has a winner-take-all dynamic where the dominant party absorbs satellite parties into a pre-electoral coalition. The result: Brazil's president is always a hostage; Mexico's president is either paralyzed (transition era) or omnipotent (PRI/Morena era). There is no stable middle ground.巴西的Centrão在每次选举中持有57-68%的众议院席位，迫使每位总统谈判。墨西哥没有Centrão——它有一个赢者通吃的动态，主导党在选前将卫星党吸收到联盟中。结果：巴西总统永远是人质；墨西哥总统要么瘫痪（转型期），要么全能（PRI/Morena时代）。不存在稳定的中间状态。
53% of votes produced 75% of seats. The system is working as designed. 53%的选票产生了75%的席位。制度在按设计运作。
Mexico uses a mixed-member electoral system for the Cámara de Diputados: 300 seats from single-member districts (first-past-the-post) and 200 seats from five regional proportional representation (PR) lists. The Constitution (Art. 54) contains an over-representation cap: no single party can hold more than 8 percentage points above its vote share. The key word is party. The cap applies to each party individually, not to coalitions. Morena won ~36% of votes and 248 seats (49.6%) — within the 8-point cap. PVEM won ~11% and got 77 seats (15.4%). PT won ~6% and got 51 seats (10.2%). Each party individually complies with the over-representation rule. But the coalition total — 53% of votes for 75% of seats — represents a 22-point gap that the Constitution does not prohibit. 墨西哥众议院采用混合选举制度：300个单选区席位（简单多数制）和200个来自五大区域的比例代表制席位。宪法（第54条）包含一项过度代表上限：任何单一政党持有的席位不得超过其得票率8个百分点。关键词是政党。上限适用于每个政党个体，而非联盟。Morena赢得约36%选票和248席（49.6%）——在8个百分点的上限内。PVEM赢得约11%选票和77席（15.4%）。PT赢得约6%选票和51席（10.2%）。每个政党单独遵守过度代表规则。但联盟总计——53%选票获得75%席位——代表了22个百分点的差距，宪法对此并不禁止。
2024 Vote Share vs Seat Share — Cámara de Diputados2024年选票份额 vs 席位份额 — 众议院
| Party政党 | Vote %得票率 | Seats席位 | Seat %席位率 | Bonus溢价 |
|---|---|---|---|---|
| Morena | ~36% | 248 | 49.6% | +13.6% |
| PVEM | ~11% | 77 | 15.4% | +4.4% |
| PT | ~6% | 51 | 10.2% | +4.2% |
| Coalition total联盟合计 | ~53% | 376 | 75.2% | +22.2% |
| PAN | ~18% | 72 | 14.4% | −3.6% |
| PRI | ~11% | 35 | 7.0% | −4.0% |
| MC | ~7% | 27 | 5.4% | −1.6% |
District effect选区效应
In 300 FPTP districts, Morena's coalition won ~210 seats despite 53% vote share — the winner-take-all dynamic magnifies the leading party's advantage in every closely contested district. Opposition votes are wasted across districts where Morena wins by any margin. 在300个简单多数选区中，Morena联盟以53%得票率赢得约210席——赢者通吃动态在每个势均力敌的选区放大了领先党的优势。反对派选票浪费在Morena以任何幅度获胜的选区。
Coalition loophole联盟漏洞
The 8% over-representation cap applies per party, not per coalition. Morena at +13.6% technically exceeds the cap, but TEPJF (electoral tribunal) assigned excess seats to coalition partners to keep each party individually compliant. The coalition total faces no constitutional limit. 8%过度代表上限适用于每个政党，而非联盟。Morena +13.6%技术上超过上限，但TEPJF（选举法庭）将多余席位分配给联盟伙伴使每个政党单独合规。联盟总计不受宪法限制。
Structural result结构性结果
A coalition with 53% popular support holds 75% of seats — enough for a constitutional supermajority. This converts electoral majorities into amendment-level power. The opposition, with 47% of votes, holds 25% of seats: insufficient to block any constitutional change. 拥有53%民意支持的联盟持有75%的席位——足以达到修宪绝对多数。选举多数被转化为修宪级权力。反对派拥有47%选票但仅持有25%席位：不足以阻止任何宪法变更。
47 constitutional amendments in one term. The fastest rewrite since 1917. 一届任期47条修宪。1917年以来最快的改写速度。
AMLO's sexenio (2018–2024) produced more constitutional amendments than any presidential term in Mexican history. The judicial reform — the most consequential structural change to the Mexican state since 1917 — moved from committee approval to floor vote in 48 hours, then to state legislature ratification within three weeks. This velocity is only possible because Congress functions as a transmission belt for presidential priorities: Morena's legislators do not deliberate; they execute. Committee chairs are allocated to Morena (82% of chairs in the Cámara, ~70% in the Senado). Bills arrive pre-drafted from the executive. Opposition amendments are voted down procedurally. Floor debate is performative. AMLO的六年任期（2018-2024）产生的修宪数量比墨西哥历史上任何总统任期都多。司法改革——1917年以来对墨西哥国家最重大的结构性变化——从委员会批准到全体投票用了48小时，再到州议会批准不到三周。这一速度之所以可能，是因为国会作为总统优先事项的传送带运转：Morena的议员不审议，他们执行。委员会主席席位分配给Morena（众议院82%的主席、参议院约70%）。法案从行政机构预先起草送达。反对派修正案被程序性否决。全体辩论是表演性的。
Constitutional amendments by presidential term按总统任期分的修宪数量
| President总统 | Term任期 | Amendments修宪数 |
|---|---|---|
| Fox (PAN) | 2000–06 | 12 |
| Calderón (PAN) | 2006–12 | 18 |
| Peña Nieto (PRI) | 2012–18 | 26 |
| AMLO (Morena) | 2018–24 | 47 |
Fox and Calderón governed with divided government (no party majority). Peña Nieto built the Pacto por México cross-party agreement. AMLO won a supermajority outright in 2024.福克斯和卡尔德龙在分立政府下执政（无党派多数）。培尼亚·涅托建立了墨西哥公约跨党协议。AMLO在2024年直接赢得绝对多数。
Key 2024 reforms — speed of passage2024年关键改革——通过速度
| Reform改革 | Committee委员会 | Floor全体 | States州批准 |
|---|---|---|---|
| Judicial (elected judges)司法（民选法官） | 48h | 72h | 18 days天 |
| GN → SEDENAGN→SEDENA | 36h | 48h | 14 days天 |
| INAI dissolutionINAI解散 | 24h | 48h | 10 days天 |
| COFECE/CRE/CNH dissolutionCOFECE/CRE/CNH解散 | 36h | 72h | 12 days天 |
For comparison: the US Affordable Care Act (2010) took 14 months from introduction to passage. Brazil's BCB independence bill took 32 years. Mexico's judicial reform — a complete redesign of the federal judiciary — took less than a month.对比：美国《可负担医疗法》（2010）从提出到通过用了14个月。巴西央行独立法案用了32年。墨西哥的司法改革——联邦司法系统的完全重新设计——用了不到一个月。
The no-reelection mechanism:禁止连任机制： Mexico's Constitution banned consecutive re-election for legislators from 1933 to 2014. A 2014 reform allowed one consecutive re-election, but its effect has been minimal: party leadership still controls candidate lists, and most legislators choose to seek other positions rather than re-election. The structural consequence is unchanged: Mexican legislators owe their political futures to party bosses, not voters. This makes Congress structurally subordinate to whoever controls the party apparatus. Under PRI, that was the president via the party machine. Under Morena, it is the president via the movement. The mechanism changed; the subordination did not. 从1933年到2014年，墨西哥宪法禁止议员连选连任。2014年的改革允许一次连续连任，但效果极小：党领导层仍控制候选人名单，大多数议员选择寻求其他职位而非连任。结构性后果不变：墨西哥议员的政治前途取决于党内领导，而非选民。这使国会在结构上从属于控制党机器的人。PRI时代，那是通过党机器的总统。Morena时代，那是通过运动的总统。机制变了，从属性没变。
The amendment pathway is always open. 26 of 32 state legislatures say yes. 修宪通道永久畅通。32个州议会中26个投赞成票。
Constitutional amendments in Mexico require (1) two-thirds of both federal chambers and (2) ratification by a majority of the 32 state legislatures (Art. 135). During the transition era (2000–2018), state legislatures were controlled by a mix of parties, making amendment ratification a genuine hurdle. After the 2024 elections, Morena and its allies control at least 26 state legislatures — nine more than the 17 needed for ratification. The amendment pathway is structurally unobstructed. Every reform the president wants can be constitutionalized, and "constitutionalized" in Mexico means beyond judicial review: the SCJN cannot strike down constitutional amendments. Morena's supermajority operates at the highest level of the legal hierarchy. 墨西哥修宪需要（1）联邦两院各三分之二通过，以及（2）32个州议会中多数批准（第135条）。在转型期（2000-2018），州议会由多个政党混合控制，使修宪批准成为真正的障碍。2024年选举后，Morena及盟友控制至少26个州议会——比批准所需的17个多出9个。修宪通道在结构上畅通无阻。总统想要的每一项改革都可以入宪，而在墨西哥"入宪"意味着超越司法审查：最高法院无权推翻宪法修正案。Morena的绝对多数在法律体系最高层级运作。
State legislature control (2026)州议会控制（2026）
| Coalition / party联盟/政党 | Legislatures controlled控制的州议会数 |
|---|---|
| Morena + alliesMorena+盟友 | 26 |
| PAN | 3 |
| MC | 2 |
| PRI | 1 |
17 of 32 needed for amendment ratification. Morena's 26 provides a 9-seat margin — enough to lose nearly a third of allied legislatures and still pass amendments.批准修宪需32个中的17个。Morena的26个提供了9席余量——即使失去近三分之一的盟友州议会仍可通过修宪。
Amendment ratification speed (2024 judicial reform)修宪批准速度（2024年司法改革）
The judicial reform was approved by the federal Cámara on September 4, 2024. Within 72 hours, 17 state legislatures had already voted to ratify — the constitutional minimum. By September 15, 23 of 32 had ratified. Several state legislatures held emergency sessions specifically to accelerate ratification. Chihuahua's legislature approved it at 3 AM after a session that began at 10 PM. Oaxaca's legislature was surrounded by protesters; legislators entered through a back door. The process was legal. It was also the fastest constitutional amendment in Mexico's modern history. 司法改革于2024年9月4日由联邦众议院通过。72小时内，17个州议会已投票批准——达到宪法最低要求。到9月15日，32个中的23个已批准。数个州议会特意召开紧急会议以加速批准。奇瓦瓦州议会在晚10点开始的会议后于凌晨3点通过。瓦哈卡州议会被抗议者包围；议员从后门进入。程序合法。这也是墨西哥现代史上最快的修宪。
Brazil's constitution requires 3/5 of both chambers (308/513 Deputies, 49/81 Senators) for amendments, and no state legislature ratification at all. This means Brazil's amendment bar is lower than Mexico's on paper — but higher in practice because no president can achieve 3/5 without negotiating with the Centrão. The United States requires 2/3 of Congress plus 3/4 of state legislatures (38/50), making the US Constitution nearly impossible to amend. Mexico occupies the worst position: a high formal requirement (2/3 + 17/32 states) that a single coalition can satisfy with room to spare. The constitution is simultaneously hard to amend and easy to control. 巴西修宪需要两院各3/5（众议院308/513、参议院49/81），且不需要州议会批准。这意味着巴西的修宪门槛在纸面上比墨西哥更低——但实际上更高，因为没有总统能在不与Centrão谈判的情况下获得3/5。美国需要国会2/3加上3/4的州议会（50个中的38个），使美国宪法几乎不可能修改。墨西哥处于最差位置：高的形式要求（2/3 + 32个州中的17个）却可以被一个联盟轻松满足并还有余量。宪法同时难以修改又容易控制。
Electoral data选举数据
Instituto Nacional Electoral (INE), official results 2000–2024. Seat allocations from Cámara de Diputados and Senado de la República official gazette. Vote share percentages for 2024 are preliminary results as published by INE's PREP program; seat allocations reflect TEPJF-certified counts.国家选举研究所（INE），2000-2024年官方结果。席位分配来自众议院和参议院官方公报。2024年得票率为INE PREP系统公布的初步结果；席位分配反映TEPJF认证的计数。
Party fragmentation政党碎片化
Effective Number of Parties (ENP) calculated using Laakso-Taagepera index on Cámara seat shares. Index formula: ENP = 1 / Σ(pi²) where pi is the proportion of seats held by party i.有效政党数（ENP）使用众议院席位份额的Laakso-Taagepera指数计算。指数公式：ENP = 1 / Σ(pi²)，其中pi为政党i持有的席位比例。
Amendment data修宪数据
Diario Oficial de la Federación (DOF), decree registry 2000–2024. Amendment counts are decrees that modified the CPEUM, counted by presidential term. Speed-of-passage metrics from congressional journals (Gaceta Parlamentaria).《联邦公报》（DOF），2000-2024年法令登记。修宪数量为修改联邦宪法的法令数，按总统任期计算。通过速度指标来自国会公报（Gaceta Parlamentaria）。
State legislature control州议会控制
State legislature composition as of January 2026, compiled from INE and state electoral institutes. "Control" defined as majority of seats held by party or pre-electoral coalition. Allied parties (PVEM, PT) counted with Morena when running on coalition tickets.州议会构成截至2026年1月，由INE和州选举研究所编制。"控制"定义为政党或选前联盟持有的多数席位。盟友党（PVEM、PT）在以联盟名义竞选时计入Morena。
Comparative data比较数据
Brazil: Cámara dos Deputados, Senado Federal, TSE. Centrão seat estimates from Project Brazil analysis. United States: Congress.gov, National Conference of State Legislatures. Amendment counts from constitution.congress.gov.巴西：众议院、联邦参议院、最高选举法院。Centrão席位估算来自巴西项目分析。美国：Congress.gov、全国州议会会议。修宪数量来自constitution.congress.gov。
Methodology note方法说明
Over-representation analysis uses INE preliminary vote tallies (PREP) and TEPJF-certified seat allocations. The 8% cap analysis is based on Art. 54 CPEUM and TEPJF jurisprudence on coalition seat distribution.过度代表分析使用INE初步计票（PREP）和TEPJF认证的席位分配。8%上限分析基于联邦宪法第54条和TEPJF关于联盟席位分配的判例。