The Rassmussen Poll put the possible 2012 opponents in a 45 - 45 per cent tie.
The same poll shows former vice-presidential republican nominee Sarah Palin would lose to Obama by a margin of 42 to 48 per cent.
The other 10 per cent in both matchups show repsondents prefer another candidate or were undecided.
The poll also showed that Romney was preferred among unaffiliated voters by a 48 to 41 percent margin over Obama.
Rassmussen's poll cited economic concerns as the main reason for Romney's popularity among likely republican voters.
----Information from: Rassmussen Reports