HARRISBURG -- More people said Democratic state Treasurer Bob Casey holds mainstream views than does Republican U.S. Sen. Rick Santorum, the man he hopes to unseat in the November election, according to an independent poll released yesterday.

Casey also continued to hold a double-digit lead over Santorum, including leads in the populous eastern and western parts of the state. Santorum leads in the 29-county central region, according to the poll by the Connecticut-based Quinnipiac University.

In the poll, 59 percent of people surveyed believe Casey holds "mainstream" views, versus 49 percent who said that about Santorum. Ten percent called Casey "extreme" compared to 34 percent for Santorum. The rest did not know enough to express an opinion, or had no opinion.

Casey also leads Santorum, the two-term incumbent who is the Senate's No. 3 Republican, by 51 percent to 36 percent. In a Keystone Poll released last week, Casey held a 50 percent to 39 percent lead. About one in 10 voters remained undecided, according to both polls.

Santorum and Casey are expected to face off in one of the most competitive and closely watched Senate races in the country. The race is expected to cost a combined $50 million, which would make it the most expensive Senate race in Pennsylvania's history.

Santorum ended 2005 with $7.8 million in cash on hand and Casey with $3.4 million, according to the latest federal campaign finance reports filed by the candidates.

The Quinnipiac survey polled 1,661 registered Pennsylvania voters by telephone and carried a sampling margin of error of plus or minus 2.5 percentage points.

Casey leads a challenger for the Democratic nomination, University of the Arts professor Chuck Pennacchio, 70 percent to 5 percent, with about two in 10 voters undecided. The poll did not include another challenger for the Democratic nomination, Philadelphia pension lawyer Alan Sandals.

Santorum faces Philadelphia real-estate broker John Featherman in the Republican primary, but the poll did not include Featherman.