A new poll of Pennsylvania voters found plunging approval ratings for President Bush, the war in Iraq and Sen. Rick Santorum, the Republican whose re-election bid figures to be one of the premier races in the country next year.

The survey, conducted by Quinnipiac University, depicted the president and Mr. Santorum with their lowest overall approval ratings since the school's researchers began polling in the state several years ago. The poll also showed that a strong majority felt that it had been a mistake to go to war in Iraq, a dramatic drop in support over the past year.

In a trial heat against his anticipated opponent next year, state Treasurer Bob Casey Jr., Mr. Santorum trailed by the daunting margin of 52 to 34 percent.

More than three in five of the voters surveyed, 61 percent, said they disapproved of Mr. Bush's performance in office while 37 percent approved and just 3 percent were undecided. A little more than a month before the 2004 election, when Mr. Bush narrowly lost Pennsylvania to the Democratic nominee, U.S. Sen. John Kerry, the state's voters were about evenly split on Bush's job performance.

A narrow plurality in the center of the state said they approved of Bush's performance, but strong majorities registered disapproval in every other region. Republicans, by and large, stood by their president, with 73 percent approving, 24 percent disapproving and 3 percent uncertain. But those were overwhelmed by the strongly negative assessments of Democrats and independents.

There was no significant gender gap in the president's numbers, with men nearly as likely as women to disapprove of his performance.

The overall approval rating for Mr. Santorum was 33 percent favorable, 30 percent unfavorable, and 19 percent mixed, while 18 percent said they hadn't heard enough about him to form an opinion on him. That was Mr. Santorum's lowest favorable score, and highest unfavorable, in more than two years.

Mr. Casey had a somewhat higher favorable rating, 38 percent, and a significantly lower unfavorable rating at just 9 percent. Mr. Casey was less well known among the voters, as 33 percent said they hadn't heard enough about him to form an opinion.

Just 43 percent of those sampled said they approved of Mr. Santorum's performance in office. As recently as February of this year, 52 percent said they approved of the way Mr. Santorum was handling his job.

U.S. Sen. Arlen Specter, R-Pa., by contrast, continued to enjoy a strong job approval rating. Fifty-seven percent of the respondents said they approved of Mr. Specter's performance, while 29 percent disapproved. The senior senator's numbers were also noteworthy in that they defied the polarization so prevalent in American politics in general, as in the findings for Mr. Bush and Mr. Santorum in this poll.

Mr. Specter's positive numbers extended across party lines with Republicans, Democrats and independents almost equally likely to approve of his performance.

The percentage of Pennsylvania voters who feel that Mr. Santorum deserves re-election has eroded throughout the year. In February, Quinnipiac found that 53 percent said that he deserved to be returned to office while 30 percent said he did not and the balance were undecided. Now, 41 percent said he deserves re-election and 42 percent said he does not.

The survey was conducted from Sept. 27 to Oct. 3, and included interviews with 1,530 registered voters. Its margin of error was plus or minus 2.5 percentage points.