(CNN) - Members of the Congressional Black Caucus disparaged former Rep. Artur Davis Tuesday, blasting the former Obama supporter for endorsing Mitt Romney this cycle.
Davis switched party affiliation from Democrat to Republican this year, two years after he failed to capture the Democratic nomination in his bid for the Alabama governorship.
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He's been in the headlines recently as a top surrogate for the Romney campaign, attributing his switch to the GOP to what he calls President Barack Obama's transition to the far left.
Fourteen members of the caucus, however, strongly took issue with Davis' decision and described his party move as a political ploy.
"Given the magnitude of your recent transformation, we can only conclude that, rather than a true conversion, your actions are the result of a nakedly personal and political calculation or simmering anguish after failing to secure the Democratic nomination for governor of the State of Alabama in 2010," the members wrote in a letter addressed to Davis.
The letter comes the same day as Davis, a former member of the caucus himself, is scheduled to speak in a primetime hour of 9 p.m. ET at the Republican National Convention in Tampa, Florida.
His high-profile speech draws a sharp contrast to his convention role four years ago, when he seconded Obama's nomination at the Democratic National Convention in 2008. At the time, he served as a co-chairman on Obama's presidential campaign.
Davis said he had hoped Obama's presidency would make a huge dent in race relations, as well as move the Democratic Party further to the center. Speaking on CNN two weeks ago, Davis also pointed to Vice President Joe Biden's controversial comments–in which he told a Virginia crowd that Romney's regulatory policies would "put y'all back in chains"–as an example of why Davis is disappointed in the current administration.
"It ought to embarrass President Obama," Davis said. "President Obama has talked so movingly about our country moving beyond race, and his own vice president makes this kind of comment yesterday? It was wrong and the president ought to be embarrassed by it, and the president ought to say it was wrong."
The 14 caucus members also referenced the former congressman's previous statements of support for Obama and Democratic views on big issues, including Wall Street reform, the stimulus bill, and the Lilly Ledbetter Fair Pay Act.
"We regret that you have chosen this course, but are confident that the American people see your pronouncements for what they are and come to the same disappointing conclusion of your former colleagues," the letter stated.
The letter was signed by the following members of Congress:
Chairman Emmanuel Cleaver (MO-05)
Rep. Corrine Brown (FL-03)
Rep. G. K. Butterfield (NC-01)
Rep Donna Christensen (VI-AL)
Rep. James E. Clyburn (SC-06)
Rep. John Conyers, Jr. (MI-14)
Rep. Donna F. Edwards (MD-04)
Rep. Marcia Fudge (OH-11)
Rep. Barbara J. Lee (CA-09)
Rep. John Lewis (GA-05)
Rep. Gregory Meeks (NY-06)
Rep. Cedric Richmond (LA-02)
Rep. Terri A. Sewell (AL-07)
Rep. Bennie Thompson (MS-02)