No, it will favor the incumbent.
It's Math.
Please explain how a third party vote from an Independent, a third party vote from a disillusioned Democrat, a third party vote from me, a third party vote from a Libertarian, and a third party vote from a Green Party pinhead, all favor Obama.
And I'd be interested to see also your mathematical proof that those five third-party votes wouln't detract from the popular mandate (as in percentage of total votes) received by either Obama or Romney.
Finny: When I vote third-party, when a Green Weenie Tree Hugger votes third-party, when a Ron Paul type votes third-party, when an Independent votes third-party, when a disillusioned Democrat votes third-party, and when a committed Libertarian votes third-party, each one of those votes will favor neither Obama nor Romney.
Mathematically-challenged Rock Lobster: No, it will favor the incumbent. It's Math.
Really! Then how is it that all the third party votes that went to Perot in 92, didn't favor the incumbent HW Bush? HMMMMMMMM???
Would you like to know why? Because your "math" is bull puckey, that's why.
And Clinton's lack of a popular mandate the first time (when 57% of Americans voted for somebody else) led to the Republican Revolution, and led to impeachment proceedings the second time (when 51% of Americans voted for somebody else).
So you are darned right it makes sense to vote third party at the top of the ticket to force a plurality and lack of mandate on whichever bastard wins, because either way, the bastard is going to be a statist who will be pushing government tyranny.