Artur Davis took the stage at the 2008 Democratic National Convention in Denver to second the nomination of Sen. Barack Obama as the Democratic nominee for president.

The congressman from Alabama was the co-chair of Obama's campaign, and he had attended Harvard Law School with the senator from Illinois. Davis' name was regularly tossed around during that fizzy period, when political watchers unironically trumpeted a supposed new school of "postracial" black politicians -- young problem-solvers and dealmakers who didn't come up through entrenched black political machines or power bases and could win over white voters.

Just four years later, when many Democrats talk about Davis, they ask the same question, with a mix of befuddlement and exasperation: What happened to that guy?

Davis is set to speak at the Republican National Convention in Tampa, Fla., and the moment stands to be the culmination of his apostasy.

"I have been encouraged by the welcome reception I have received from Republicans, from national officials to old congressional colleagues to the Virginia Republican Party," Davis told The Huffington Post. "What has been a pleasant surprise is the volume of supportive email from rank-and-file Republicans that follow television appearances or attacks from Democrats."

Davis says the words "race" and "African American" will not appear in his convention speech.

"While my leaving the party has gotten attention for predictable reasons -- a former Obama supporter, African-American elected official and all that -- the reality is that according to Gallup, 9 percent of Obama supporters do not plan to vote for Barack Obama," Davis told The Huffington Post's Jon Ward. "He got 70 million votes. That translates, even by my math, into 6.3 million people."

Behind the scenes, Democratic officials say that Davis' switch was an attempt to stay in the spotlight, and last week, the Democratic National Committee released an ad to that effect. The spot used Davis' words against him, turning his previous pro-Obama convention address about the promise of an Obama presidency into an itemized list of Obama's White House accomplishments. "Artur Davis' speech at the GOP convention isn't about Barack Obama ... It's about Artur Davis," the ad concluded.

Davis brushed aside the spot. "My old Democratic friends are reminding me of an old rule: In politics, if you fear someone is getting through and people are listening, attack them as fast as you can," he said. "I do wish they had not reminded me that I have gained weight in four years."

It's been a wild ride to this point. When Davis first won the House seat that represents Birmingham, Ala., in 2002, it was a shock to the local Democratic order. After a bruising primary, he'd managed to unseat Earl Hilliard, the first black congressman the Yellowhammer State had sent to Washington since Reconstruction and a politician many people thought was unbeatable. Hilliard's strategy, in part, rested on portraying Davis as not black enough, a tactic used against Barack Obama in Chicago, Mayor Cory Booker (D) in Newark and former Rep. Harold Ford (D) in Tennessee. Davis, then 34, countered by stitching together an unconventional coalition of disaffected black voters in his district and donors from the coasts. He portrayed the old guard, which grew out of the civil rights movement, as out of touch and, nationally, appealed to Jewish voters upset by Hilliard's critiques of Israel.

But Davis was never really all that liberal. Once he landed in Congress, he voted for the Federal Marriage Amendment that would have banned same-sex marriage. He voted to allow drilling for oil and gas in Alaska's National Wildlife Refuge. And most notably, or notoriously, depending on whom you ask, Davis broke party ranks with the rest of the Congressional Black Caucus to vote against President Obama's signature health care law, criticizing it as too expensive and unwieldy. Jesse Jackson said at the time, "You can't vote against health care and call yourself a black man."

Those stances, and the distancing from Alabama's black political power structure, were seen as an attempt by Davis to bolster his conservative credentials and his independence from Obama in deeply red Alabama, with an eye on the state's governorship.

The political repercussions were resounding and total. Though polls had Davis up by 30 points in the Democratic gubernatorial primary, he ended up being throttled by Ron Sparks, who was white, even among black voters. Sparks beat Davis by 70 percent in some black Alabama counties.

"You have to understand. I love Artur like a son," U.W. Clemon, the state's first black federal judge, told the Birmingham News at the time. "I've never personally known a politician with more intelligence, more gifts than Artur, with the exception of President Obama."

"But, I also have to say that I've never been more disappointed in a person in my life," Clemon said about Davis' no vote on the health care law. "Artur walked away from the people who needed him the most, and he walked away from himself."

Even though Davis' star may have dimmed in some eyes, his appearance at the Republican convention is not without its political benefits. It needles the other side -- think Sen. Joseph Lieberman (I-Conn.), just eight years removed from his nomination as the Democratic Party's vice presidential nominee, stumping for John McCain in 2008. But there's also the signal Davis' speech sends, with one of the president's most high-profile black supporters defecting and criticizing him so publicly.

"I don't spend time worrying about people who base their personal loyalties on politics or who view support for Mitt Romney as some act of racial disloyalty," Davis said Sunday.

He's gestured toward another possible congressional run in Virginia, although he demurred when asked if his plans had become more concrete. And he said that despite anemic support from voters of color, Republicans still have a case to make to those communities. "It will take two things: a seriousness about using conservative values to close some of the gaps that exist in society, and an understanding that conservatism cannot just be a defense of economic liberty, it must engage ways to promote upward mobility and opportunity for the middle class and the poor."

Since his switch, Davis has been a vocal proponent of voter ID laws, which he maintains are necessary for preventing voter fraud. But voting fraud is virtually nonexistent, and voting rights groups have warned that such laws will keep many blacks, Latinos and young people from voting, since those groups are less likely to have government-issued ID. Significantly, those groups are also much more likely to vote for Democrats.

Davis was defiant when asked if he faced any personal fallout by switching sides.

"More amusing are the individuals who were political antagonists who dress themselves up as former friends to get their name in the paper," Davis said. "I also appreciate the many Democrats who tell me privately that they are embarrassed by the party's attacks and sense a personal bitterness in the attackers."

Gene Demby covers politics for Huffington Post BlackVoices. You can follow him on Facebook and Twitter.

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  • Artur Davis

    This Feb. 6, 2009, file photo, shows former Rep. Artur Davis, D-Ala., in Montgomery, Ala. Davis is shifting his voter registration to Virginia and says that if he seeks public office again, it will be as a Republican. Davis, who represented Birmingham in Congress for four terms and then unsuccessfully sought the Democratic nomination for Alabama governor in 2010, announced his decision on his website Tuesday, May 29, 2012. (AP Photo/Dave Martin, File)

  • Will Shift To GOP If He Runs For Office Again

    This Aug. 27, 2008, file photo shows former Rep. Artur Davis, D-Ala., at the Democratic National Convention in Denver. Davis is shifting his voter registration to Virginia and says that if he seeks public office again, it will be as a Republican. Davis, who represented Birmingham in Congress for four terms and then unsuccessfully sought the Democratic nomination for Alabama governor in 2010, announced his decision on his website Tuesday, May 29, 2012. (AP Photo/Paul Sancya)

  • Artur Davis Explains Why He Converted To GOP

  • As A Democrat, He Was Highly Visible At The 2008 DNC

    Artur Davis delivers a seconding speech formally placing Barack Obama's name into nomination as candidate for U.S. President for the Democratic Party in 2008.

  • As A Democrat, He Voted Against Health Care Reform

    WASHINGTON - MARCH 19: Rep. Artur Davis (D-AL) talks on the phone while standing on a balcony outside the U.S. Capitol March 19, 2010 in Washington, DC. Davis, who is running for governor of Alabama, voted against health care reform legislation last year and said he would do the same when the bill comes before the House this weekend. (Photo by Chip Somodevilla/Getty Images)

  • DNC Attacks Artur Davis In 2012 Campaign Ad

  • Commemorating The Historic Selma March

    SELMA, AL - MARCH 04: (L-R) U.S. Congressman Artur Davis (D-AL), Rev. Al Sharpton, Democratic Presidential candidate Senator Hillary Clinton, U.S. Congressman John Lewis (D-GA) and former President Bill Clinton pray before and induction ceremony of National Voting Rights Museum Hall of Fame following a march to the Edmund Pettus Bridge to commemorate the 1965 'Bloody Sunday' Voting Rights march March 4, 2007 in Selma, Alabama. Bill Clinton was one of the inductees into the hall. During the 1965 march, which was to go from Selma to Montgomery, Alabama, police used tear gas and beat back the marchers when they reached the Pettus Bridge. (Photo by Scott Olson/Getty Images)

  • Honoring The AARP

    In this photograph taken by AP Images for Points of Light, Points of Light Board Member and former Rep. Artur Davis and AARP Board Chairman Phil Zarlengo, right, unveil a medallion honoring AARP founder Dr. Ethel Percy Andrus during a ceremony on the Extra Mile - Points of Light Volunteer Pathway, Wednesday, Oct 12, 2011 in Washington. The Extra Mile Pathway is a national monument in the heart of Washington that honors those who selflessly championed causes to help others realize a better America. (Kevin Wolf/AP Images for Points of Light)

  • Participating On A U.S. Department Of Agriculture Panel