REPLACING ONE MODERATE WITH ANOTHER…. Arlen Specter left the Republican Party when Pennsylvania Republicans rejected his relative moderation. Pessimistic about Pat Toomey’s chances, GOP leaders have been scrambling, looking for a credible Republican alternative.

It appears the party has rallied behind former Gov. Tom Ridge (R) as their new go-to guy. Ridge, a two-term chief executive and the first DHS Secretary, is probably the only Republican with a realistic shot at winning the statewide race.

There are, however, a couple of problems. First, Ridge lives in Maryland, not Pennsylvania, and as Rick Santorum can attest, Keystone State voters tend to care about whether their candidates live in the same state as they do.

Second, there’s the inconvenient fact that Ridge isn’t that much more conservative than Specter. If the party’s far-right base found Specter intolerable, Ridge, whose pro-choice views were rumored to have kept him off the McCain ticket, may find himself vulnerable to attacks from the right.

They’ve apparently already started.

The first shots have been fired: National Review’s David Freddoso takes a quick look at Ridge’s record as a congressman (1983-95), and finds it worrisome on a number of fronts to conservatives:

While in Congress, writes Freddoso, Ridge “voted to expand welfare eligibility (1984), to fund abortions with public money, and in favor of the fairness doctrine (in 1987).”

“Ridge voted against an early school choice program in 1992,” Freddoso continues.

Ridge also “voted against an early school choice program in 1992,” the article states. “He also voted for a number of union priorities — in 1988, he voted to re-hire the air traffic controllers who had gone toe-to-toe with President Reagan seven years earlier and lost.”

Conservative Matt Lewis, after noting some of Ridge’s controversial lobbying work, questions how Pennsylvania primary voters might react when the former governor’s record draws closer scrutiny.

… What will happen when Pennsylvania Republicans find out that Ridge voted for the outrageous Fairness Doctrine in 1987 that would force radio stations to “balance” conservative talk show hosts like Rush Limbaugh with liberal hosts?

… What will happen when PA Republicans find out that Ridge went out of his way to oppose President Reagan’s Missile Defense efforts, voting against funding for the program numerous times?

… What will happen when voters find out that Ridge voted to send taxpayer dollars to the National Endowment for the Arts to be spent on obscene and indecent work, including child pornography?

It’s very early, and there’s at least some evidence that Ridge would be heavily favored to beat Toomey in a GOP primary. But given Ridge’s occasional moderation, Toomey and other conservative activists are no doubt drawing up plans to make the former governor look like their up-until-recently Republican senator, and they’ll have plenty of material to work with.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.