Party Loyalty Scorecard & Rebel Tracker: Who's Defying Their Party in the 119th Congress

The 119th Congress is operating in one of the most partisan environments in American legislative history. A vote study published by CQ Roll Call on March 5, 2026 confirmed that 2025 set an all-time record: 85.3 percent of congressional roll call votes were "party unity votes" — meaning a majority of each party voted on opposite sides. That's more than 10 percentage points above the previous record of 74.6 percent set in 2023.

In a Congress where going along with your party is the overwhelming norm, who stood out? Which members voted against their own side most often — and who maintained a perfect record of loyalty? Here's the full breakdown.

Senate: Near-Perfect Republican Cohesion

Senate Republicans delivered a historic show of unity in 2025, voting together an average of 96 percent of the time on party unity votes. They won 577 of 616 total party unity votes — a 93.7 percent win rate — shattering their previous record of 89.7 percent set in 2017, the first year of President Trump's first term. Senate Democrats held together at an average 92 percent party unity rate.

[ANALYSIS] The CQ Roll Call study notes that the record was inflated in part by procedural mechanics: cloture votes on nominations count as party unity votes under their methodology, and Republicans cast hundreds of them to advance Trump's nominees. The underlying totals still reflect an unprecedented level of partisan alignment, per the study's authors.

Senate Rebel Tracker

Even in this hyper-partisan environment, a handful of senators consistently broke from their caucus. On the Republican side, the top three defectors were all members who had long positioned themselves as independent voices — and who made headlines in 2025 for crossing the aisle on tariff legislation.

Sen. Lisa Murkowski (R-AK) led Republican defectors at 13.4 percent, followed closely by Sen. Susan Collins (R-ME) at 12.7 percent. Both senators voted with Democrats to rebuke President Trump's tariff policies in October 2025, joining Sens. Rand Paul (R-KY) and Mitch McConnell (R-KY) on measures disapproving of Trump's 10-percent global tariffs and additional levies on Canada and Brazil. Tillis also joined on the Brazil measure. Sen. Rand Paul (R-KY) rounded out the top three GOP defectors at 11.8 percent. Paul has stated on the Senate floor that his crossover votes on tariffs and war powers reflect his view that Congress must assert its constitutional role on executive authority. [ANALYSIS]

On the Democratic side, Sen. John Fetterman (D-PA) led the caucus for party deviation in 2025, voting against his party on approximately 20 percent of unity votes — the highest rate among members who caucused with Democrats, per the CQ Roll Call study. [ANALYSIS] The Roll Call vote study named Fetterman as "effectively taking the mantle" from former Sen. Joe Manchin (D-WV) as the most likely Democratic member to cross party lines. His most recent high-profile crossover came on Senate Vote #46 on March 4, 2026, when he was the sole Democrat to vote against the motion to discharge the Iran War Powers resolution, S.J.Res.104.

New Hampshire senators Shaheen and Hassan — both representing a state with competitive general-election dynamics — each bucked their party more than 15 percent of the time. Independent Sen. Angus King (I-ME), who caucuses with Democrats, crossed over on 92 unity votes (15 percent of those he cast).

House Rebel Tracker

In the House, Democratic members were more likely to break from their caucus than Republicans. [ANALYSIS] Political analysts and the Roll Call study both note a correlation between high deviation rates and representing Trump-won or competitive districts — a pattern consistent with the members ranked highest on this list.

Rep. Henry Cuellar (D-TX) was the single House member most likely to break with his party — from either side of the aisle — crossing over on 35.9 percent of all party unity votes. Cuellar represents a South Texas district that Trump carried and has long been one of the most conservative Democrats in the chamber, frequently bucking his party on immigration, energy, and fiscal votes. He was also the House Democrat most likely to back Trump on presidential support scores published in February.

Rep. Marie Gluesenkamp Pérez (D-WA) followed at 31.1 percent, and Reps. Jared Golden (D-ME) and Don Davis (D-NC) each defied their party on roughly 30 percent of unity votes. All four represent districts that Trump carried in 2024, and all were among the most Trump-aligned Democrats on the presidential support tabulations.

On the Republican side, Rep. Brian Fitzpatrick (R-PA) was the most frequent crossover voter in his conference, opposing the GOP position on 18.9 percent of party unity votes. The co-chair of the Problem Solvers Caucus and sole Republican representing a district that Kamala Harris carried, Fitzpatrick also voted against Trump's position on nearly one-third of presidential support votes — the highest rate of any House Republican.

The Party-Line Loyalists: Perfect Unity Scores

At the other end of the spectrum, dozens of members voted with their party on every single contested vote in 2025. Among House members eligible to participate in the full year of unity votes:

• 34 House Democrats had perfect party unity scores, voting with the Democratic caucus on all 254 unity votes they cast.
• 29 House Republicans had perfect scores, including Reps. Kevin Hern (R-OK), Ronny Jackson (R-TX), and Roger Williams (R-TX).

In the Senate, perfect unity was rarer given the higher volume and complexity of votes:

• 14 Senate Republicans eligible for at least half of unity votes maintained perfect records.
• 3 Senate Democrats voted with their party on every unity vote they cast: Sens. Patty Murray (D-WA), Tina Smith (D-MN), and Chris Van Hollen (D-MD).

Key Crossover Moments: When Party Lines Broke

The most significant defections of 2025 came on trade and war powers — areas where ideological fault lines have historically cut across party affiliations.

The "One Big Beautiful Bill" (H.R. 1) — the sweeping GOP reconciliation law that extended and expanded the 2017 tax cuts, cleared Congress without a single Democratic vote. The House passed the final version on House Roll Call #190 on July 3, 2025. See H.R. 1 on Congress.gov. According to the CQ Roll Call vote study, 86 of the Senate's 616 party unity votes in 2025 were related to this legislation and its two preceding budget resolutions.

Tariff rebuke votes (October 2025) — Four Senate Republicans — Collins, McConnell, Murkowski, and Paul — crossed party lines to join Democrats in passing resolutions disapproving of Trump's global tariff policy; Sen. Thom Tillis (R-NC) also joined on the Brazil-specific measure. Those votes were among the few genuine Republican defections of the session and represent the clearest signal that trade remains a policy fault line within the GOP coalition.

Iran War Powers (S.J.Res. 104, March 4, 2026) — The most recent major crossover vote saw Sen. Rand Paul (R-KY) vote with Democrats and Sen. John Fetterman (D-PA) vote with Republicans on the Senate Vote #46 motion to discharge, which failed 47–53.

What to Watch in 2026

The early weeks of the 119th Congress's second session suggest partisan pressure remains intense. The DHS shutdown standoff has held firm along party lines for more than three weeks. Iran war powers votes in both chambers this week produced only a handful of crossovers. If anything, the members most likely to break from their parties — Fetterman, Fitzpatrick, Cuellar, Murkowski — are under heightened scrutiny heading into a 2026 midterm cycle that will test the limits of each party's coalition.

CVT will continue tracking these scores on a rolling basis throughout the 119th Congress.