A report by the Lugar Center and Georgetown University’s McCourt School of Public Policy ranked how bipartisan each senator is.
The list intends to measure how well members of opposite parties work with one another.
The rankings were made using bill sponsorship and co-sponsorship data and hopes to “fill a hole in the information available to the public about the performance of Members of Congress.”
Other measures of bipartisanship have ranked members of Congress by partisan, parochial or special-interest standards. This report used sponsorship information because solely using a members’ voting record, for instance, might not be the most accurate representation on bipartisan work, since votes can be influenced by factors other than the lawmaker’s stance on issues, the report said.
The report noted that using bill sponsorship data differs greatly by which party holds the majority and said the rankings took into account which senators co-sponsored many bills.
“We tested solutions to each of these questions and others before settling on what we believe is an effective formula for measuring bipartisanship,” the report said.
If a member is ranked low on the list, they are considered to view their role in Congress through a partisan lens. If they’re ranked high on the list, it’s a strong indication that they prioritize problem solving and are open to working across the aisle, the report said.
The 10 most bipartisan senators in 2023, according to the list:
Susan Collins (R-Maine)
Sen. Susan Collins (R-Maine) has held her seat since 1997 and is Maine’s longest-serving member of Congress and longest-serving woman in the Senate. She’s described herself as a “pro-choice” Republican and introduced the Reproductive Choice Act to codify Roe v. Wade.
Gary Peters (D-Mich.)
Sen. Gary Peters (D-Mich.) has served since 2015. A gun owner, he was one of 40 senators in 2019 to introduce the Background Check Expansion Act. The Senate unanimously passed his bipartisan bill that would ensure military families can be buried together.
Maggie Hassan (D-N.H.)
Sen. Maggie Hassan (D-N.H.) was elected to the Senate in 2016. She participated in the bipartisan Trump administration task force focused on rebuilding the economy during the COVID-19 pandemic and introduced legislation that requires federal agencies to deliver reports to Congress about terrorist attacks.
Joe Manchin (D-W.Va.)
Sen. Joe Manchin (D-W.Va.) has held his seat since 2010. He described himself as a “centrist, moderate conservative Democrat” who is “not a Washington Democrat.” In the past, Manchin has introduced and co-sponsored several bills focused on veterans.
John Cornyn (R-Texas)
Sen. John Cornyn (R-Texas) has served in the Senate since 2002. He overwhelmingly supports conservative ideologies but in the past has teamed up with Democrats to tackle gun safety measures. In 2017 he authored the Fix National Instant Criminal Background Check System Act for gun purchases, which was praised by many associations.
Jacky Rosen (D-Nev.)
Sen. Jacky Rosen (D-Nev.) has served Nevada in the Senate since 2019. She said she is proud of her bipartisan and moderate reputation and will focus on her state over “politics or party loyalty.” In response to rising rates of antisemitism, she introduced a bill that would establish a national coordinator for antisemitism.
Lisa Murkowski (R-Alaska)
Sen. Lisa Murkowski (R-Alaska) has held her seat since 2002. She introduced bipartisan bills aimed to streamline federal response to climate change caused natural disasters. She’s also worked with Manchin to urge other lawmakers to advance a reauthorization of the Voting Rights Act to secure order in elections.
Jerry Moran (R-Kan.)
Sen. Jerry Moran (R-Kan.) was elected in 2010. He’s the co-sponsor of the bipartisan Transporting Livestock Across America Safely Act, which reformed hours of service for drivers to allow for rest. He also introduced legislation that would allow Afghan refugees to apply for permanent legal residency.
Todd Young (R-Ind.)
Sen. Todd Young (R-Ind.) has held his seat since 2017. Along with Democratic Senate Majority Leader Chuck Schumer (N.Y.), Young co-sponsored the 2022 CHIPS and Science Act, focused on bolstering the American semiconductor industry.
Jon Tester (D-Mont.)
Sen. Jon Tester (D-Mont.) was elected to the Senate in 2006 and known as a moderate or centrist Democrat. Elected to a red state, he often has sided with Republicans on gun rights and the economy, but generally supports Democratic ideologies.
Updated at 2:58 pm EST.