It's tactics like this that make the average American hate politics...

From Electoral Vote:

There is also more political news from the bench, in Louisiana. Incumbent congressman Rodney Alexander, who was elected as a Democrat, switched parties and filed for reelection as a Republican 20 minutes before the filing deadline so the Democrats would not have a chance to field an opponent. He was instantly embraced by the Republican party and showered with good will and money. The other guys went to court and the judge said the Democrats had to have a chance to submit a candidate. This decision was reversed on appeal and the state Supreme Court just declined to hear the case. Consequently, the Republicans will almost certainly pick up a House seat in the 5th CD in LA. Moral of the story: dirty tricks work.