Pennsylvania Sen. Arlen Specter trails a lesser-known challenger in the 2010 Republican primary, an indication of the political hit he has taken in his party's base for giving crucial support to the Democratic-drafted $787 billion economic stimulus, according to a new poll.

Former Rep. Pat Toomey, a conservative leader from the Lehigh Valley, leads Specter 41 to 27 percent in a hypothetical matchup in a Quinnipiac University survey released today.

Although Toomey came within 17,000 votes of beating Specter in the 2004 GOP primary, the poll found that 73 percent of Republican voters did not know enough about the likely challenger to form an opinion of him. Seventy-eight percent of all voters had not heard of Toomey.

"Pennsylvania Republicans are so unhappy with Sen. Specter's vote for President Barack Obama's stimulus package and so-called pork barrel spending that they are voting for a former congressman they hardly know," said Clay F. Richards, assistant director of the Quinnipiac University Polling Institute. "Toomey came close last time and has strong conservative backing, but his challenge could be fractured if more Republicans crowd into the primary and split the anti-Specter vote."

Specter's support for the stimulus won 87 percent to 6 percent approval among Democrats; and 56 percent to 38 percent support among independents. Republican voters disapprove of that vote by a whopping 70 percent to 25 percent.

Overall, voters approve of the job Specter is doing 52 percent to 33 percent, boosted by strong support from Democrats and independents. That was nearly reversed among Republicans, however, with 36 percent approving Specter's performance and 52 percent disapproving.

Quinnipiac surveyed 1,056 Pennsylvania voters by telephone from March 19 through March 23. Results are subject to a margin of error of plus or minus 3 percentage points; the survey includes 423 Republicans, with a margin of error of plus or minus 4.8 percentage points.