Bipartisanship Index: Measuring How Often Congress Crosses the Aisle in the 119th Congress

The 119th Congress has given us two data points that seem impossible to reconcile. In May 2025, the House passed the One Big Beautiful Bill Act by 215–214 — not a single Democrat voted yes. Nine months later, the same body passed the Housing for the 21st Century Act by 390–9. The Senate followed at 89–10. Same Congress. Same members. Opposite outcomes on bipartisanship.

That contrast is the story of the 119th Congress in two numbers. Not a contradiction — a pattern. Congress operates in two distinct modes depending on what's on the floor, and understanding that pattern is more useful than any single headline about gridlock or cooperation.

This is CVT's Bipartisanship Index for the 119th Congress, 2nd Session: a systematic look at which votes crossed party lines, which didn't, and what explains the gap.

How CVT Defines a Bipartisan Vote

For this analysis, a Senate vote is classified as bipartisan when at least 5 members of the minority party vote with the majority on a final passage, cloture, or substantive amendment vote. Procedural votes — motions to proceed, quorum calls, simple scheduling motions — are excluded unless they carried substantive political stakes.

Why 5 votes? In the current Senate (53 Republicans, 45 Democrats, 2 Independents who caucus with Democrats), 5 minority votes represent roughly 11% of the 47-member Democratic caucus. That's a meaningful signal of cross-party agreement — not a rounding error, not a single defector making noise.

This threshold is conservative by design. It's meant to capture genuine cross-party coalitions, not the occasional outlier. The Lugar Center Bipartisan Index, an established academic measure, uses a similar principle of meaningful minority-party participation.

2026 Senate Bipartisanship Scorecard

CVT reviewed all substantive Senate roll call votes from the 119th Congress, 2nd Session (January 3 – March 15, 2026). The full 2nd Session vote list contains 54 recorded votes as of this writing; many are routine judicial confirmations decided along party lines. Here are the politically significant votes and their bipartisanship scores:

The Polar Cases: Housing vs. One Big Beautiful Bill

The sharpest contrast in the 119th Congress isn't between the two parties — it's between two bills that reveal when bipartisanship is achievable and when it isn't.

H.R. 1, the One Big Beautiful Bill Act, was signed into law on July 4, 2025 as Public Law 119-21. Not one Democrat voted for it in either chamber. The Senate needed Vice President J.D. Vance's tiebreaker after three Republicans — Collins (R-ME), Paul (R-KY), and Tillis (R-NC) — voted against the bill. The House version passed by a single vote: 215–214, with Massie (R-KY) and Spartz (R-IN) crossing to the opposition. By any measure, this was the most partisan major legislative outcome in recent memory.

Nine months later, the Housing for the 21st Century Act passed 390–9 in the House and 89–10 in the Senate. Both chambers. Both parties. Near-unanimous. The contrast isn't just striking — it demands an explanation.

What Makes Bipartisanship Possible? Five Patterns from the Data

Looking at every bipartisan vote in the 2nd Session, five conditions reliably predict whether a bill or nominee will attract cross-aisle support:

1. The policy doesn't touch partisan hot-button issues. The housing bill avoided immigration, taxes, abortion, and gun policy — the four categories where party discipline is near-absolute. It focused narrowly on zoning and housing supply, a policy area where neither party had a rigid ideological position.

2. Both parties have constituent-facing benefits. Every senator from every state has housing-cost-burdened constituents. The bill created a direct line between a yes vote and lower housing costs in every member's backyard. When the constituent benefit is universal, party discipline weakens.

3. The bill's framing works for both coalitions simultaneously. Republicans called the housing bill "cutting regulatory red tape." Democrats called it "making housing affordable." Both were accurate descriptions of the same legislation. A bill that can be honestly framed two ways simultaneously is a bill that can win two parties.

4. Strong bipartisan committee leadership. The partnership between Sen. Tim Scott (R-SC) and Sen. Elizabeth Warren (D-MA) — not an obvious political pairing — gave both parties trust in the process. The Scott-Warren amendment on investor restrictions passed 84–10, nearly the same margin as the bill itself. Co-authorship across the aisle matters.

5. No electoral penalty for crossing over. On the housing vote, there was no political cost to voting yes for members of either party. On OBBB, every Democratic yes vote was a potential primary vulnerability and a gift to Republican messaging. The asymmetry of electoral risk shapes the vote before debate even begins.

What Kills Bipartisanship: The DHS Case Study

If the housing bill illustrates when cooperation is possible, the DHS appropriations fight shows when it isn't. The government shutdown affecting DHS funding has now produced four consecutive failed cloture votes, all failing to reach the 60-vote threshold needed to end debate. The pattern is consistent: Republican votes barely crack 52, and Democrats hold virtually unanimous opposition.

The core dispute centers on immigration enforcement and CBP accountability provisions — exactly the kind of issue where both parties face maximum partisan pressure. Democrats who crossed over would face primary challenges. Republicans who voted no would be painted as soft on border security. The electoral math makes cooperation nearly impossible regardless of what individual senators privately believe.

The lone exception: Sen. John Fetterman (D-PA), who voted with Republicans on the fourth cloture attempt and has now broken with his caucus on multiple immigration-adjacent votes in the 119th Congress. Fetterman's willingness to cross over on DHS funding makes him the most notable bipartisan actor on the Democratic side — and the most isolated.

Who Crosses the Aisle Most?

[ANALYSIS] Based on the vote patterns documented in this analysis and the broader 119th Congress record, several senators stand out as the most consistent cross-aisle voters:

On the Republican side: Sen. Lisa Murkowski (R-AK) and Sen. Susan Collins (R-ME) are the most frequent Republican crossovers on healthcare, housing, and appropriations — and both voted against H.R. 1. Sen. Rand Paul (R-KY) regularly votes with Democrats on libertarian-adjacent foreign policy positions, including the Iran War Powers resolution.

On the Democratic side: Sen. John Fetterman (D-PA) now leads his caucus in crossover frequency. Sen. Mark Kelly (D-AZ) has a documented pattern of bipartisan votes on defense and security matters. Both senators voted for the Rudd CYBERCOM/NSA confirmation at 71–29.

For a comprehensive member-by-member bipartisan scoring, GovTrack's full report cards provide individual vote histories with partisan analysis.

Timeline: Bipartisan Moments in the 119th Congress

What's Next: House Floor Week of March 16

The bipartisanship story isn't over. H.R. 6644 must return to the House for a concurrence vote on the Senate-amended version. Given the House's original 390–9 margin, a lopsided bipartisan concurrence is widely expected. If the House accepts the Senate amendment, the bill goes directly to President Trump's desk — potentially the most bipartisan bill signing of his second term.

Meanwhile, the DHS funding impasse enters what would be week five without a resolution. There is no visible bipartisan path on immigration enforcement until at least one side faces a political cost larger than the cost of continued shutdown. The GovTrack bills calendar shows additional legislation queued for the House floor, but none appears to carry the bipartisan momentum of the housing bill.

[ANALYSIS] The 53% bipartisan rate among substantive 2026 Senate votes is arguably higher than public perception of congressional dysfunction would suggest. But that number is heavily influenced by the housing bill's extraordinary run — six consecutive bipartisan votes on the same legislation. Strip those out and the 2026 rate looks considerably more partisan. The 119th Congress isn't unusually cooperative. It has one unusually cooperative issue — and everything else looks a lot like recent history.