National Republican Senatorial Committee Chairman John Cornyn (Texas) may have called for Pennsylvania Republicans to unite behind Sen. Arlen Specter (Pa.) last week, but GOP members of the Keystone State delegation are choosing to sit on the sidelines in what is expected to be a blockbuster primary in 2010.

The state’s Republican House Members indicated in separate interviews that they are not ready to endorse Specter, who faces a challenge next year from former Rep. Pat Toomey (R-Pa.) in what is likely to be the toughest battle of his 30-year Senate career.

Specter enjoyed the support of almost everyone in the delegation in 2004, when he narrowly defeated Toomey by less than 2 percent in the GOP primary. But with Specter trailing Toomey in polling on next year’s rematch, Pennsylvania Members aren’t inclined to choose sides for now.

Rep. Bill Shuster (R-Pa.), who supported Specter in the last primary, told Roll Call recently that he had not endorsed anyone yet — and that he plans to keep it that way for the time being. “Right now I’ve not endorsed anyone,— Shuster said. “Now it’s too early to get out there.—

Shuster was one of nine Republicans in the delegation who supported Specter in 2004. Rep. Joe Pitts was one of the state’s two Republican Members who stayed neutral in the last primary (then-Rep. Melissa Hart was the other). Pitts said he doesn’t plan on changing that position six years later.

“I’ve got two friends fighting,— Pitts said. “I’m not going to get between them.—

Pitts said he has not spoken with Toomey for months but considers both Toomey and Specter to be personal friends.

“I served with Pat. I served with Arlen,— Pitts said. “And whoever wins, I’ve got to live with them, and I’m not going to get between them if they fight, if they’re the two.—

Not only did Rep. Jim Gerlach (R-Pa.) support Specter in 2004, but the Senator’s family lives in his suburban Philadelphia district. Gerlach, who is considering a bid for governor in 2010, had nothing but praise for Specter — but stopped short of endorsing the Senator. “I’ve worked with Sen. Specter on a lot of things,— Gerlach said. “And he’s been very helpful to the 6th Congressional district.—

Another 2004 Specter supporter, Rep. Tim Murphy (R-Pa.), said through his top aide that he was not going to endorse either candidate yet. Murphy’s chief of staff, Susan Mosychuk, said the Congressman is declining to make public statements about any of the races in Pennsylvania.

Even freshman Rep. Glenn Thompson (R-Pa.), who was elected to his first term last November, declined to say who he would support in 2010.

“In 2010, there is one extremely important race for me and that’s my re-election, honestly,— Thompson said. “That’s what I’m focusing on.—

The other two Republicans in the delegation, Reps. Charlie Dent and Todd Platts, did not respond to several requests for comment. Dent was elected to succeed Toomey in his Allentown-based district in 2004.

Member endorsements were particularly useful to Specter in his 2004 race, when support from then-Reps. John Peterson (R-Pa.) and Don Sherwood (R-Pa.) helped the moderate Republican win votes in some of the most conservative areas in the state. Then-Sen. Rick Santorum (R-Pa.) also played a key role in barnstorming for Specter and helping to woo conservatives, but Santorum lost re-election in 2006.

Peterson recalled that he and Sherwood did press conferences with Specter and appeared in television advertisements with him, both of which helped to boost his conservative credentials in their respective districts.

“If we both had supported Toomey, I think Toomey would have won,— Peterson said. “Toomey did not do as well there as he did in all the neighboring districts.—

This time around, however, Peterson said he would not support Specter for re-election. He said the 80-year-old incumbent should consider retirement, and his advice to him would be to “go enjoy your grandchildren.—

“I don’t think you’d find me supporting 80-year-olds for re-election,— Peterson said. “It’s not disrespect for him, but there is a time.—

Former Rep. Phil English (R-Pa.), who lost in November, also supported Specter in 2004. Although he plans to support the Senator again in 2010, he said he believes he could be in the minority of Pennsylvania Republicans, in part because of Specter’s support for the stimulus bill.

“I think what is going on here is that the House delegation was very strongly opposed to the so-called stimulus bill,— English said. “I do think that Sen. Specter did a remarkable job of being perhaps the one Republican or the one group of Republicans to actually have an impact on moderating that product, but I think that at the end many Republicans feel a very strong tide running against deficit spending in Washington. I think that’s obviously going to be a very big factor in this election.—

Not only are there fewer Republicans supporting Specter for re-election, the Pennsylvania Republican delegation has also nearly been cut in half since he ran for re-election five years ago. English’s district is one of five Republican-held seats that Democrats have picked up in the state since 2004.

The dwindling ranks represent an even larger problem for the eventual Republican nominee, who will then face a general election in an increasingly Democratic state. Former National Constitution Center President Joe Torsella is the only announced Democrat in the race, although several others are considering running. In fact, at least three southeastern Pennsylvania lawmakers are considering a bid: Reps. Joe Sestak, Allyson Schwartz and Patrick Murphy.

Many Republicans, including English, are arguing that Toomey would not be a viable candidate in the general election.

In a letter to Pennsylvania Republicans last month, Cornyn stressed Specter’s ability to hold onto the seat in the general election as one of the major reasons the NRSC is backing him. “As I survey the political landscape of the upcoming 2010 elections, it’s clear we need more candidates that fit their states,— Cornyn wrote.

As the May GOP primary draws nearer next year, English emphasized that many Republicans might realize that Specter is their best shot to keep the seat in 2010.

“I do think the picture is going to look different over time as we approach the Pennsylvania primary,— he said.