Sen. Rick Santorum's approval rating has skidded to a four-year low, the latest sign of distress for the outspoken conservative and ally of President Bush, according to a poll released Wednesday.

The lead for Santorum's Democratic opponent, state Treasurer Bob Casey, has stretched to 18 percentage points since early May.

Casey leads Santorum by 52 percent to 34 percent _ the biggest margin since October, when the numbers were the same, according to the Quinnipiac University poll.

Only 38 percent of respondents said they approved of the way Santorum, the third-ranking Republican in the Senate, is handling his job. Forty-five percent said they disapproved and 16 percent did not express an opinion.

It was the first time Santorum's approval rating dropped below 40 percent since Quinnipiac began measuring it in June 2002.

Bush's approval rating in the state rebounded somewhat in the latest poll, to 34 percent from 30 percent in May. The proportion of Pennsylvania voters who approved of Bush's handling of the war in Iraq increased to 35 percent from 29 percent.

"Senator Santorum appears to be his own worst enemy in his battle for re-election,"said Clay F. Richards, assistant director of the Connecticut-based university's polling institute.

In the May survey, Casey, the son of late Democratic Gov. Robert P. Casey, led Santorum by 49 percent to 36 percent.

More than 40 percent of Casey's supporters said they are more against electing Santorum to a third term than for Casey, the poll showed.

Virginia Davis, a Santorum campaign spokesman, said polls are unreliable at this stage in the campaign. Santorum plans to air the first statewide TV commercials of his campaign on Friday, she said.

Larry Smar, a spokesman for the Casey campaign, agreed that it is too early to read too much into the polls but that Casey's continuing strength in polling bodes well for the November election.

Quinnipiac conducted telephone interviews with 1,076 Pennsylvania voters between June 13 and Monday. The results carry a sampling margin of error of plus or minus 3 percentage points.

On the Net:

Quinnipiac polls in Pennsylvania:http://www.quinnipiac.edu/x11378.xml

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