The Senate's Top Cross-Party Voters
Sen. Susan Collins (R-ME) holds the highest congressional bucking rate in the Senate during the 119th Congress, voting against her own party 28.9 percent of the time, yet her reelection campaign has become a battleground over the opposite claim: that she votes too often with the president. Collins leads the Senate in cross-party voting, followed closely by Sen. Lisa Murkowski (R-AK) at 27.3 percent and Sen. Rand Paul (R-KY) at 24.8 percent. All three of the Senate's top cross-party voters are Republicans.
Collins' 28.9 percent bucking rate exceeds Murkowski's 27.3 percent by 1.6 percentage points, the narrowest gap among the top three Senate crossers listed. Paul trails Murkowski by a wider margin, at 24.8 percent.
Collins has embraced her reputation for bipartisanship, highlighting on her official Senate website a designation as the chamber's "most bipartisan member," a title credited to the Lugar Center and Georgetown University.
A Contested Record
That same record has become a point of contention in her reelection campaign. Following his June 9 Democratic primary victory, former challenger Graham Platner argued that Collins voted "with Donald Trump 95% of the time," a claim reported as accurate by NEWS CENTER Maine with respect to her voting pattern in 2025.
The tension between those two characterizations reflects a genuine methodological distinction: a bucking rate measures how often a member votes against the majority of their own party, while a presidential support score measures alignment with the White House's stated position. A senator can rank high on one metric and high on the other simultaneously, depending on how often the party and the president diverge.
The House Crosses Party Lines Further
The House shows even higher cross-party voting rates among its top members. Rep. Henry Cuellar (D-TX-28) leads the chamber with a bucking rate of 31.6 percent, exceeding Collins' Senate-leading 28.9 percent by 2.7 percentage points.
Cuellar is followed by Rep. Thomas Massie (R-KY-4) at 28.8 percent and Rep. Donald Davis (D-NC-1) at 27.2 percent. Unlike the Senate's top three, the House's top cross-party voters split between parties, with the two highest bucking rates belonging to a Democrat and a Republican respectively.
Cuellar's January Vote
Cuellar's cross-party record includes a January 2026 vote in favor of the Department of Homeland Security (DHS) Appropriations Bill, which passed with the support of Cuellar and six other Democrats joining the Republican majority to avoid a government shutdown.
Despite criticism from fellow Democrats, Cuellar defended the vote by pointing to oversight provisions and spending guardrails he said he helped include in the legislation. In a Jan. 22 press release, Cuellar said: "Passing this bipartisan compromise ensures these investments and oversight measures take effect. The alternative would have delivered none of them."
What the Numbers Show
The top bucking rates in both chambers cluster in a narrow band. In the Senate, the gap between Collins at 28.9 percent and Paul at 24.8 percent spans just over four percentage points across the top three. In the House, the spread from Cuellar at 31.6 percent to Davis at 27.2 percent covers a similar range.
The composition of the top tier differs by chamber. In the Senate, the three members most likely to break with their party are all Republicans, suggesting that the primary source of cross-party movement in that chamber currently runs from right to center. In the House, the top two crossers come from opposite parties, with a Democrat leading the list, pointing to cross-party pressure operating in both directions.
For lobbyists and congressional staff tracking legislation that requires bipartisan support, these members represent the most predictable points of potential coalition-building, at least as measured by their voting histories. A bill that needs to peel off Republican votes in the Senate would logically look first to Collins, Murkowski, and Paul. A measure needing Democratic support in the House would look to Cuellar and Davis.
All voting data was provided by Legis1 as of June 24, 2026.
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