In a Congress riven by partisan acrimony, it's hard to find members respected on both sides of the aisle. While the Senate has a reputation for respectful proceedings and close friendships, regardless of ideology, the House is more combative. Think Newt Gingrich. Think Cynthia McKinney.

But a standout in those roiling partisan waters is John Lewis, a liberal Democrat whom even ultraconservative Republicans don't like to cross. Lewis may not be a living saint — though Time magazine described him that way back in 1986 — but he is hardworking, principled and conscientious. That's reason enough to send him back to Congress.

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For the first time in several years, however, Lewis is having to make his case to voters. He has drawn two primary opponents, a development that can probably be traced to Lewis' early endorsement of Hillary Clinton in the Democratic race.

Watching as Barack Obama won Georgia handily on Feb. 5, some ambitious Dems believed they could paint Lewis as out of touch, over the hill. So "Able" Mabel Thomas, a state legislator, and Markel Hutchins, a community activist, decided to challenge him.

Both Thomas and Hutchins have résumés that show modest achievements. A former Atlanta City Council member now serving in the Georgia House, Thomas has long been involved in issues affecting poorer neighborhoods. Hutchins made a name for himself by demanding accountability in the aftermath of the botched police raid that resulted in the shooting death of elderly homeowner Kathryn Johnston. As a result, he has become known as an advocate for police reforms. But neither comes close to Lewis' stature or stellar record.

Lewis' principles have never wavered. A determined believer in nonviolence, he has always stood against war, voting against U.S. military action in the Persian Gulf in 1991 and again in 2002. He was among the first Democrats to suggest impeachment proceedings against George W. Bush, arguing that the president "deliberately, systematically violated the law" in authorizing eavesdropping without warrants. "He is not king, he is president," Lewis said.

Because of his near-mythic status as a young field marshal in the civil rights movement, even conversatives bowed to Lewis when he pushed to renew the Voting Rights Act of 1965. Though several Republicans had suggested it was time to end government oversight of election law in Southern states, Lewis insisted that racism still haunts too many precincts. Though Congress was still controlled by Republicans in 2006, the Voting Rights Act was extended.

As for his endorsement of Clinton, Lewis spoke eloquently about his decision in an essay published in The Atlanta Journal-Constitution in January. He noted that both "senators Obama and Clinton are dear friends of mine." Indeed, he agonized for months over choosing between them.

As for his critics, "I did not get arrested and go to jail 40 times, I did not get beaten and left for dead in a Greyhound bus station in Montgomery, I did not spill a little blood on the Edmund Pettus bridge to be harassed and intimidated for supporting the candidate of my choice. ... To suggest that people who endorse a different candidate are members of 'the old guard' or bound by a 'slave mentality' demeans their ability to arrive at a thoughtful conclusion," he wrote.

But as a man who put his life on the line to secure the franchise for every citizen, he respected the power of the ballot. He yielded to the will of Georgia's Democratic voters and endorsed Obama in late February.

When Obama secured the nomination, Lewis seemed overjoyed. "If someone had told me this would be happening now, I would have told them they were crazy, out of their mind, they didn't know what they were talking about. I just wish the others [leaders of the civil rights movement] were around to see this day," he said.

Few did more than Lewis to help Obama — and America — arrive at this moment. And few have done more to move the nation forward on its journey toward "a more perfect union." Lewis still has more work to do, and he needs to be in Congress to get it done.

• Cynthia Tucker is the editorial page editor. Her column appears Wednesdays and Sundays.