Missouri Democratic Reps. William Lacy Clay Jr. and Russ Carnahan once cordially represented St. Louis together, but they are now squared off in a reelection effort that has them calling each other desperate, angry liars and even Tea Party allies.
That's what can happen when two members of Congress are matched up in a single district because of a once-every-decade redrawing of political boundaries.
In St. Louis and Detroit, a decades-long exodus of urban residents has forced districts to be combined. As a result, Democratic primaries on Tuesday could reduce the cities' black representation in the U.S. House to their lowest levels since the 1960s.
Republican representatives will face off this month in Florida and Arizona, states that gained House seats after the 2010 census. In those races, the incumbents are competing to represent the most politically advantageous areas.
Overall, 11 contests this year have pitted incumbents against each other. Some are highlighting the tea party tensions inside the Republican Party and racial sensitivities among Democratic constituents.
"It's just devastating to the Democratic Party here that people have to make these kind of choices, when there are two good candidates," said Claude Brown, 72, a Democratic activist in St. Louis who is siding with Clay largely because of loyalties to Clay's father. William Lacy Clay Sr. represented St. Louis for 32 years in the House, from 1969 to 2001, and was succeeded by his son.
Carnahan's grandfather served in Congress. His father, Gov. Mel Carnahan, died in a plane crash in October 2000 while campaigning for the U.S. Senate. Russ Carnahan won election to the House in 2004.
When Missouri lost a seat as a result of the census, the Republican-led Legislature, with the help of a few urban Democrats, carved up Carnahan's south St. Louis area district and merged it with others. Instead of moving to a Republican-leaning suburb, Carnahan chose to battle Clay for the shrinking core of St. Louis.
Clay, who is black, holds a demographic advantage in the district where a majority of the remaining residents are racial minorities. Carnahan, who is white, is trying to appeal to voters by claiming Clay has sold out to shady lenders preying on low-income residents who live paycheck to paycheck.
Clay has received tens of thousands of dollars over the past few years from the rent-to-own industry.
Carnahan's campaign has mailed greeting-card style fliers that, when opened, play a snippet of a Clay speech to a 2008 convention of rent-to-own retailers in which Clay expresses pride in successfully advancing their interests. Other Carnahan fliers call his rival "Payday Clay."
Carnahan also accuses Clay of "throwing Democrats under the bus" by allegedly supporting the Republican redistricting plan that squeezed St. Louis into one district instead of two.
Clay says Carnahan should quit "whining" about redistricting. He claims Carnahan "has run a desperate, angry campaign," and accuses him of "voting with the tea party" by not supporting a certain Democratic alternative to a Republican budget plan.
Playing up his connections to urban voters, Clay is running a hip-hop radio ad in which a rapper disses the tea party, boasts of Clay's "backbone" and proclaims in rhyme that Clay "stands for the people each day" and "battles for us, better than Russ."
In a debate this past week, Clay and Carnahan repeatedly accused one another of telling "whoppers."
In the GOP versus GOP primaries this month, the matchups are at least partly voluntary and a carry-over of the conservative wave that swept through the party in 2010.
In Arizona, for example, a redistricting commission placed the home of Rep. Ben Quayle, the son of former Vice President Dan Quayle, in a newly drawn 9th Congressional District that includes more Democrats than his old territory did. Instead of running there, Quayle chose to challenge fellow freshman Rep. David Schweikert in the Republican-leaning 6th District.
Schweikert, who has the support of some tea party groups, complained at the time: "He's making a selfish move that puts Republicans in a very tough position."
In central Florida, longtime Rep. John Mica and freshman Rep. Sandy Adams are running in the redrawn 7th District instead of shifting to a newly created district that lacks an incumbent.
Mica, the chairman of the House Transportation and Infrastructure Committee, has the endorsement of former Arkansas Gov. Mike Huckabee, a onetime presidential candidate. Adams has the endorsement of former Alaska Gov. Sarah Palin, the party's 2008 vice presidential nominee. The race pits an established Republican against a tea party upstart, with the focus on budget cuts, pet projects spending and who's the most conservative.
Michigan Reps. Gary Peters and Hansen Clarke have remained generally civil in their Detroit area Democratic primary. Yet Clarke, the son of a Bangladeshi man and a black woman, has refused to participate in campaign debates because of what he described as "racist rhetoric and race-baiting by certain candidates." He has not accused anyone by name. Clarke recently began running radio ads aimed at black voters, proclaiming he's "one of us" while asserting that Peters lives in Republican presidential candidate "Mitt Romney's old neighborhood" in the suburbs.
Peters, who enjoys a fundraising advantage, has the endorsement of Detroit Mayor Dave Bing and is the first white House candidate supported by The Black Slate, a Detroit activist coalition. If Peters prevails, and longtime Rep. John Conyers stumbles in a four-way Democratic primary, Detroit could be left with no black representation the House. The same would be true for St. Louis, if Clay loses.
Since their peak in 1950, the populations of Detroit and St. Louis both have declined by more than 60 percent, and it's predominantly white residents who have left.
Although not overtly stated in campaigns, "there's no question that race plays a big role," said Ken Warren, a political science professor at Saint Louis University. "Polarized voting is an electoral reality. Blacks vote for blacks, whites vote for whites, Italians vote for Italians, Mormons vote for Mormons."