ORLANDO, Fla.  Seeking any advantage in their effort to retain control of Congress, Democrats are working behind the scenes in a number of tight races to bolster long-shot third-party candidates who have platforms at odds with the Democratic agenda but hold the promise of siphoning Republican votes.

The efforts are taking place across the country with varying degrees of stealth. And in many cases, they seem to hold as much risk as potential reward for Democrats, prompting accusations of hypocrisy and dirty tricks from Republicans and the third-party movements that are on the receiving end of the unlikely, and sometimes unwelcome, support.

In California, Republicans have received recorded phone calls from a professed but unidentified “registered Republican” who says she is voting for the American Independent Party’s candidate for a House seat, Bill Lussenheide, not for the incumbent Republican, Mary Bono Mack.

The caller says she is voting that way because “it’s time we show Washington what a true conservative looks like.”