The accusations range from helping tea party activists circulate candidate petition sheets to underwriting the creation of official tea parties, which then put forth slates of candidates that local conservatives accuse of being rife with Democratic plants.

In all of the affected races, the outcome is expected to be close enough that a third-party candidate who wins just a few percentage points could end up swinging the outcome to the Democratic congressman or candidate…

[T]he evidence of campaign tampering in at least two states is hard to dismiss. In Michigan, the party chairman in suburban Detroit’s Oakland County now concedes that one of his top aides played a role in helping nine tea party candidates get onto the ballot for various offices across the state — including the open 1st Congressional District and the 7th Congressional District, held by vulnerable freshman Democratic Rep. Mark Schauer.