If that could happen, then the system is seriously broken.
Political parties are not constitutional entities; they can select their nominee any way they like, with whatever criteria they like.
But the general election is governed by the Constitution; it SHOULD be the case that the FEC certifies eligibility before putting anyone's name on the ballot.
Whether that's really the case or not; I cannot say.
I address your comment here but I am also addressing the comments of several other respondents.
The general election is governed to some extent by the Constitution, but not the way you apparently think it is. The States are in charge. The States don't even have to have elections for the electors for President if they choose not to. Individual States are free to appoint electors or decide them by a lottery. The FEC is a (probably unconstitutional) creation of Congress whose charter is to see that the elections the States hold are "fair" and that no one who the Federales think should be allowed to vote is denied that opportunity.
Obama's name may be on the ballot when people vote but no one is actually casting a for Obama. Obama, even if ineligible for the Presidency, is free to support these electors. The question I raised is what would happen if the electors voted in the majority for someone who is ineligible, and his election were certified by Congress. You, and others here, have ignored this as if the entire Electoral College system were meaningless. It's not, to some of us.
ML/NJ
Oh, man! Where to begin?
The Constitution does not authorize or provide for a "general election". The STATES are authorized to set up a mechanism (more precisely, the state legislatures are so authorized) to choose Electors. It just so happens that all 50 state legislatures have chosen to use a popular vote to choose their Electors, they are not required to do so.
Where in the Constitution do you find authority for something called a "Federal Election Commission"? The idea that the Federal fox is "in charge" of the electoral henhouse, while very popular around here, is repugnant to the Constitution, and the FEC has no authority which any patriot is bound to respect.
The check on Obama's illegitimacy is the People, by any means necessary. If that is insufficient, we are lost and no phony commissions or pretended court decisions can save us.