Republican presidential candidate Mitt Romney has surged to level pegging with Rick Santorum in the Ohio primary, setting up a cliffhanger race tomorrow, according to a poll released yesterday.

The two are tied with 32% support from voters in the Ohio Republican primary, the most important of the 10 state contests on "Super Tuesday" this week.

After his victory in Saturday's Washington state caucuses, Mr Romney is gaining momentum after trailing Mr Santorum.

"This race could really go either way," said Ipsos pollster Chris Jackson."If Mitt Romney is able to close this out and win this race, that gives him a leg up in going all the way."

Ohio is a traditional bellwether state, and will play a key role in deciding which Republican candidate challenges President Barack Obama in November's election.

The poll showed Newt Gingrich on 17%, and Ron Paul, from Texas, with 6%.

Asked who they would back in a two-man race, 44% said they would support Mr Romney, while 43% would support Mr Santorum.

The poll showed voters were responding to the candidates for different reasons. Of Mr Romney's backers, around two in five felt he has a better chance of beating Mr Obama and improving the still-tepid economy. More than half of Mr Santorum's backers were interested in his conservative principles on issues such as abortion.