Santorum was on the advisory board of the Michigan-based Thomas More Law Center, which defended the district's policy. The law center describes its mission as defending the religious freedom of Christians.
''I thought the Thomas More Law Center made a huge mistake in taking this case and in pushing this case to the extent they did," Santorum said Wednesday. He said he would end his affiliation with the center.
The leading Democratic challenger in Santorum's 2006 re-election battle, state Treasurer Robert P. Casey Jr., accused him of backtracking on intelligent design.
Casey spokesman Larry Smar said Wednesday that Santorum's statements were ''yet another example of 'Election Year Rick' changing his positions for political expediency." Casey has led Santorum in recent polls.
Richard Thompson, president and chief counsel of the center, said Santorum's withdrawal came as no surprise because several weeks earlier the senator had indicated that he was unhappy with the center's involvement in the case.
''It is a very controversial issue, as you know, and he is involved in a very hotly contested Senate race, and it's probably in his best interest," Thompson said yesterday.
US District Judge John E. Jones ruled Tuesday that the Dover district's policy of requiring students to hear a statement in biology class about intelligent design was ''a pretext . . . to promote religion" in public schools.
Intelligent design's proponents hold that living organisms are so complex that they must have been created by a higher force.
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