Speaking last night before the GOP convention, former representative Artur Davis described how disappointment with President Obama prompted his recent conversion to the Republican Party. "May it be said of this time in our history, 2008 to 2011, lesson learned," said Davis, who served for eight years as a Democratic House member. "2012: mistake corrected."

Former representative Artur Davis addresses the Republican National Convention in Tampa on Tuesday. (J. Scott Applewhite/Associated Press)

Both parties have embraced and elevated such party-switchers as evidence of their opponents' misdeeds: Former Florida governor Charlie Crist, the Republican-turned-Independent, is similarly slated to speak next week at the Democratic convention.

Despite the hype they attract, the number of party-switchers in Congress, at least, has been relatively low in recent decades and largely the outgrowth of Southern Democrats like Davis who've switched to the Republican Party. They reliably change their votes to reflect their new parties' views, but they have a consistently harder time getting elected, according to Antoine Yoshinaka, a political science professor.

Since the 1960s, 33 sitting members of Congress have switched parties, by Yoshinaka's count: 22 were Democrats switching to the GOP, seven were Republicans switching to the Democratic party, and the remaining four went Independent. (He excludes ex-members like Davis, who switched after he was out of office.)

Regional political shifts have been the single biggest factor. "The most fertile ground for party switching has been the South, where Democratic officeholders have switched to the GOP in droves," Yoshinaka explains in an interview. "The trend really started after Reagan's election, picked up in the 1990s and is still ongoing today."

In that regard, Davis's switch in Alabama is hardly an anomaly: It's becoming increasingly hard to win as a Democrat in the South. The major difference is that the southern Democrats who switch tend to be white, while Davis is African American. But the rise of politicians such as freshman Rep. Tim Scott, the first black Republican to be elected to Congress in South Carolina, suggests that the shift is becoming broader as the South has become increasingly Republican.

That said, it could still be hard for Davis to be reelected as a Republican, which he says he'd consider doing. Political parties have good reason to embrace party-switchers: Aside from the PR boost, party-switchers fairly reliably change their votes to reflect their new parties' views, as political scientists Nolan McCarty, Keith  Poole and Howard Rosenthal have found. But the general public is more suspicious. "Voters punish members who switch parties," Yoshinaka writes in a 2011 paper he co-authored with Christian Grose. "On average, switchers lose about seven percentage points in all elections after they switch."

Davis switched parties after losing as a Democratic candidate for governor in 2010. But even as a Republican, Davis could face an upward climb with voters if he decides to run for office again.