Republican presidential frontrunner Mitt Romney has erased rival Rick Santorum's lead among voters in Santorum's home state of Pennsylvania which holds a crucial primary next month, a poll on Wednesday showed.
Santorum, who represented the state in Congress for 16 years until he was defeated in a Senate election in 2006, saw his lead over Romney evaporate from 29 points to 2 points in the past month, according to the Franklin and Marshall College poll conducted from Lancaster, Pennsylvania.
Pennsylvania's primary election takes place on April 24, along with liberal northeastern states like New York and Connecticut which Romney is favored to win.
If Santorum loses or scrapes by with a narrow win in Pennsylvania, he will come under pressure from senior Republicans to pull out of the race.
Thirty percent of likely Republican voters said they would vote for Santorum and 28 per cent chose Romney, creating a statistical tie, according to the poll.
In February, Santorum led Romney 45 per cent to 16 per cent, the poll said.
Santorum's drop in Pennsylvania can be attributed to his emphasis on social conservativism over the past month, the director of the poll said. In and around Philadelphia, Republicans are moderate on issues such as abortion rights and gay marriage.
''These cultural issues are not popular with the voters in the eastern part of the state,'' said Terry Madonna, a professor at Franklin and Marshall College.
The poll surveyed 505 Pennsylvania Republican registered voters and the margin of error was plus or minus 4.2 percentage points. Santorum did best in central and western Pennsylvania and Romney polled better in the southeastern and northeastern parts of the state.
Almost a quarter of voters polled said they were undecided.
''Many Republican voters want this over. They see this as divisive. They don't see this helping their candidate in the fall at all,'' Madonna said.