Republican presidential candidate Rick Santorum, in what may be a grim development for his campaign, has lost the lead in his home state of Pennsylvania to front-runner Mitt Romney, according to a poll released on Thursday.
Romney now leads in Pennsylvania with 42 percent to 37 percent for Santorum, according to the Public Policy Polling survey. Ron Paul was at 9 percent and Newt Gingrich at 6 percent, the poll found.
"Mitt Romney has a great chance to deliver a final crushing blow to (Santorum's) campaign on April 24th," said Dean Debnam, president of the polling firm.
Santorum has been banking his hopes on recapturing some momentum in the race by winning Pennsylvania's primary. He is the last remaining obstacle for Romney, who is closing in on the nomination after sweeping Republican contests on Tuesday in Wisconsin, Maryland and Washington D.C.
Santorum had been a U.S. senator from that state until 2006, when he was defeated by double digits. A devout Catholic, he is taking several days off the campaign trail to observe the long Easter weekend, his spokesman said.
Pennsylvania's primary is one of five northeastern states to hold nominating contests on April 24. The group includes New York and Connecticut, where Romney, a former governor of nearby Massachusetts, has been favored to win.
If Santorum loses or scrapes by with just a narrow win in his home state, he will come under increased pressure from senior Republicans to pull out of the race.
Karl Rove, a former strategist for President George W. Bush, called Santorum a "fading candidate" in an opinion piece Thursday for the Wall Street Journal and shot down Santorum's argument that a prolonged nomination race would energize the party ahead of the general election.
"That's the argument of a desperate candidate. More and more Republicans think such a bloodletting would severely set back the cause of defeating Barack Obama," Rove wrote.
Thursday's poll also showed Romney gaining among conservative groups that have previously tended to back Santorum.
A previous 37-point lead for Santorum over Romney among evangelicals has shrunk to 10 points, and what was a 32-point lead among Tea Party supporters is now only 6 points, according to the poll.
The poll surveyed 403 likely Republican voters by phone on Wednesday. The margin of error was plus or minus 4.9 percent.