This is great news for Republicans. If Trump were to declare a third party candidacy, it would almost certainly keep New York Mayor Michael Bloomberg from running, and might even make Ron Paul hesitate given how much cash Trump could throw around.

Trump would pull far fewer voters than either Bloomberg or Paul from the GOP.

CNN:

Donald Trump continued to tease a potential presidential run by changing his voter registration Thursday from Republican to "unaffiliated" and publicly denouncing the behavior of members of his former party.

Michael Cohen, an aide to Trump, said the real estate mogul and reality television star made the switch "in order to preserve his right to run for president as an independent if he's not satisfied with who the Republicans nominate."

The change was made with the New York State Board of Elections.

Cohen added that Trump was "disgusted with the way Republicans are handling" the payroll tax cut extension, saying the actions of Republicans were partly to blame for his party change.

Cohen also cited foreign policy issues, claiming Trump had been ahead of the curve in predicting security issues in Iraq after the U.S. pulled out troops.

"Iraq is imploding. Who else has been saying this except Trump?" Cohen said.

The answer is everyone, but don't tell The Donald that.

A Donald Trump third party candidacy would be the ultimate exercise in vanity and narcissism. He wouldn't have a prayer of even taking one state and, as I mentioned, would hurt the GOP far less than any other potential third party challenger.

Still, in close states like VA, NC, and perhaps CO, Trump's few thousand votes might spell the difference between victory and defeat much like Ralph Nader's votes tipped the state for George Bush in 2000. Hopefully, it won't matter as much either.