Both were elected to Congress in 1992, Feinstein to the Senate and Graham to the House of Representatives, from which he graduated to the Senate a decade later. Since then they’ve established relatively centrist voting records.

In an analysis of dozens of key votes last year that was released last week, the National Journal placed Graham as more conservative than 13 Republican senators and less conservative than 32. It placed Feinstein as more liberal than 25 Democratic senators and less liberal than 25.

Each senator has shown a willingness to break with party leaders on high-profile issues.

Feinstein opposed the North American Free Trade Agreement, a top first-term initiative of Democratic President Bill Clinton, and declined to back his attempt to overhaul health care. Under Republican President George W. Bush, she broke with most other Democratic senators in supporting his 2001 tax cuts.

After a partisan House career in which he led the push to impeach Clinton and derided the president’s initiatives as “an agenda that makes you want to throw up,” Graham became more of an unpredictable maverick in the Senate.

He criticized Bush’s conduct of the Iraq War and, as a military lawyer, helped craft major legislation that placed restraints on the interrogation, detention and trial of suspected terrorists.

He’s been a fierce opponent of Democratic President Barack Obama, most recently in opposing his nomination of former Sen. Chuck Hagel, R-Neb., as defense secretary and demanding more information about the terrorist assault last Sept. 11 on the U.S. consulate in Benghazi, Libya, which killed four Americans.

Yet during Obama’s tenure, Graham has worked with Democratic senators on climate change, immigration and measures to punish China for its alleged currency manipulation and human rights violations.

Known for his quick wit, Graham on Tuesday followed Feinstein, who’d said she didn’t deserve to receive the civility prize. He prompted roars of laughter from the audience in quipping: “Dianne, I don’t deserve it either, but I don’t deserve most of the crap I get, either, so I’ll take it.”

Graham criticized the 2010 Supreme Court ruling in Citizens United v. Federal Election Commission – in which the high court struck down limits on campaign contributions from outside groups – as contributing to the rancor in Washington. Since the ruling, he said, a flood of interest-group money has increased partisanship.

“A lot of it has to do with money,” he said. “Citizens United was not a good decision, in my view. Politics is awash with money.”

Allegheny College President James H. Mullen Jr. urged the congressional colleagues of Feinstein and Graham to follow their example.

“If every politician were to emulate the instincts of Dianne Feinstein and Lindsey Graham, we would be a better democracy,” Mullen said.

PBS commentators David Brooks and Mark Shields received the civility prize last year, the first time it was awarded by the Pennsylvania college founded in 1815.