Declaring himself a "doer and a fighter," U.S. Rep. John Lewis (D-Atlanta) on Monday kicked off his first political campaign in eight years.

"Some people talk about change. I am change," said Lewis, to a crowd of enthusiastic supporters gathered at his Northside Drive campaign headquarters. "No one, but no one will out-work or out-campaign me.

"When I'm not in Washington voting, I'll be out here campaigning," Lewis said. "you're going to be sick of me."

Lewis faces the biggest challenge of his 22-year career as a U.S. congressman.

For the first time since 1992, Lewis faces, not one, but two challengers from within his own party. Lewis hasn't faced an election opponent since 2000, when he crushed GOP challenger Hank Schwab.

One of Lewis' July Democratic primary challengers is a 31-year-old Atlanta minister and community activist, the Rev. Markel Hutchins.

The other is longtime state Rep. "Able" Mable Thomas (D-Atlanta), 50.

Both challengers say Lewis, 68, is an aging civil rights-era veteran who has grown out of touch with his Atlanta constituents. Lewis, at least publicly, appears eager for the fight.

When asked last week about his two-front primary challenge, the one-time lieutenant of the Rev. Martin Luther King replied, "I'm going to give them a nonviolent kick."

Political observers say it's possible, if not likely, that Hutchins and Thomas will fare a little better than any of Lewis' past challengers, none of whom carried a third of the vote.

Hutchins has never held political office. In Thomas' first try at Lewis' seat, she carried only 24 percent of the 1992 Democratic primary vote against Lewis. Neither challenger appears to have the financial or political clout at this point to beat Lewis.

But their candidacies alone may suggest there at least is a crack in his iconic stature. Hutchins and Thomas point to Lewis' presidential endorsement reversal as a main reason.

Last October, Lewis endorsed Democrat Hillary Clinton for president.

"I have looked at all the candidates, and I believe that Hillary Clinton is the best prepared to lead this country at a time when we are in desperate need of strong leadership," Lewis said at the time.

Georgia voters, including 5th District voters, did not agree. They overwhelmingly voted for Barack Obama for president on the state's Feb. 5 presidential primary.

Ten days after the primary, The New York Times reported that Lewis was switching to Obama. The same day, an aide to the congressman called the story "inaccurate," but wouldn't cite the specific error.

For nearly two weeks, Lewis refused to say who he was endorsing for president. On Feb. 28, he threw his support to Obama.

Bob Holmes, a fellow Democrat and a retiring Georgia lawmaker from Atlanta, says the Obama-Clinton endorsement flap hurt Lewis, but not nearly enough to imperil his re-election chances.

"What's their secondary issue?" asked Holmes of Hutchins and Thomas. "If it [the endorsement controversy] doesn't take hold with voters, what are they going to take him on for?"

Holmes predicted that Lewis would win the July 15 Democratic primary without a runoff.

"I'll say he [Lewis] gets 60 plus percent of the vote," said Holmes.

David Bositis agreed that Lewis will likely win an easy re-election contest. Bositis, a specialist in black electoral politics with the Joint Center for Political and Economic Studies in Washington, said the endorsement controversy will be largely forgotten by election time.

"The fact is, he did switch," Bositis said.