WASHINGTON (AP) - President Barack Obama's re-election effort is paying close attention to two candidates mounting third-party campaigns for the presidency, believing they could draw votes from Republican rival Mitt Romney and help Obama win a few tightly contested states.

One candidate is Virgil Goode, a former conservative Virginia congressman who is running as a member of the Constitution Party. The other is Gary Johnson, a former two-term Republican governor of New Mexico who is the Libertarian Party's presidential nominee.

Obama's team has scenarios whereby Obama can win states like Virginia and Colorado with less than 50 percent of the vote, with an assist from Goode and Johnson.

Romney aides say his supporters are too committed to defeating Obama to vote for a third-party candidate.