US election 2012: a President Romney and Vice President Biden administration? The 12th amendment has only been invoked once, in 1824, when the electoral college was split between four candidates. A draw, or tie to Americans, would be a first. But it is not implausible, given that there are 12 swing states are up for grabs. As each state has a different number of electoral votes, there are permutations which could have avid election watchers on tenterhooks on the night. The two candidates could end up all square if Mr Obama retained only New Hampshire, Ohio and Wisconsin out of those 12 states. But give him one more state and he wins. Another map that produces a draw would see the president win Colorado, Iowa, New Hampshire and Virginia. Tad Devine, a veteran Democratic consultant, told Politico: "I think 269-269 could happen. That's not a remote possibility, it's a real possibility. Whit Ayres, a Republican pollster, agreed: "It is more likely this year because of the incredible closeness of the race." Most states operate a system by which the winner of a state takes all its electoral college votes. The electors then meet in December to formally appoint the president. However, the allocation of electors may not be clear for days if one or more races are extremely close. Both parties have small armies of lawyers at the ready in case of disputed ballots, problems with vote counting or claims of voter fraud or exclusion. A further complication is that two of the 50 states, Nebraska and Maine, do not operate a winner-takes-all system; they allocate electors according to results in congressional districts and could therefore in effect operate a casting vote in the college, which has 538 electors. Experts think that in the event of a draw, Democrats would think it unrealistic to force Mr Biden on Mr Romney, and would decide to allow the Republican to take his running mate Paul Ryan as his vice-president. Whichever candidate lost the popular vote could also come under moral pressure to concede. Another controversial, and perhaps more likely, outcome is that Mr Romney wins the popular vote but loses the electoral college, because of Mr Obama's strength in swing states. This would be a repeat of the 2000 campaign, when Al Gore won the popular vote but lost the electoral college by five votes to George W Bush after the Supreme Court intervened to stop a recount in Florida. With high stakes negotiations over balancing the federal budget supposed to completed by the end of the year, that is a prospect that fills many with dread.