Heading into the final weeks of his re-election primary battle, Sen. Arlen Specter (R-Pa.) is pulling all the levers of incumbency in an effort to maximize every institutional advantage at his disposal.

With signs of a tightening race against Rep. Pat Toomey (R), Specter is going to great lengths to mix both his official duties and his political activities to try to stamp out the conservative challenge to his bid for a fifth term.

Just last week Specter held two official events that his supporters hoped would drive home a message that he’s got the full support of his Senate colleagues and the Bush White House.

Criss-crossing the state, Specter, chairman of the Senate Veterans Affairs Committee, held a field hearing March 22 in Erie listening to constituent concerns regarding efforts to close VA hospitals. Earlier that day Specter was on a farm northwest of Pittsburgh with Agriculture Secretary Anne Veneman to announce a program handing out cash to local farmers near fragile land.

A week earlier, March 15, Specter flew on Air Force One and was on stage with President Bush outside Philadelphia to bask in the glow of hearing Bush tell the audience that Specter was an “ally and a friend” who is “doing a fine job as a United States Senator.” (For Bush’s purposes, the event was to promote home ownership and his own electoral prospects in the fall.)

Mixing in the official events between the campaign work allows Specter to gain attention for his Senatorial activities — by holding field hearings and attending taxpayer-funded events with Bush and Cabinet officials — without having to spend a dime out of his campaign account. That helps save money for a TV ad campaign with a stated goal of doubling the amount of time Toomey and his interest-group allies purchase on air.

Specter’s aides deny that his field hearings and official activities were timed to benefit his campaign, contending that he is a workhorse who would be holding these events regardless of his election prospects. “That’s him, period. That’s what he does anyway,” said Bill Reynolds, Specter’s spokesman. “That is something we would have done regardless of the race.”

But this theme of official and political business will only continue in the run-up to the April 27 primary, with his Veterans Affairs field hearings taking place in a few other locations in the state.

The Judiciary Committee last month also granted him subpoena power for an antitrust subcommittee hearing on a nettlesome health-care issue in Philadelphia on April 12, barely two weeks before the primary.

Just as importantly, Specter’s political activities have been littered with big-name Republicans coming into the Keystone State to promote the 74-year-old, including valuable campaign work by two Senate Republican leaders, Majority Whip Mitch McConnell (R-Ky.) and Conference Chairman Rick Santorum (R-Pa.). McConnell, whose leadership political action committee has already donated the maximum $10,000 for Specter’s primary and general election battles, plans to campaign for Specter on April 19.

Santorum, the leading conservative voice in Pennsylvania politics, has doggedly worked for Specter and tried to inoculate him from attacks from Toomey and right-leaning interest groups working to defeat Specter. Santorum even cut an ad for Specter that ran heavily throughout the state.

“He is using everything available regarding fundraising and getting his colleagues out for him,” said Reynolds. “As he puts it, he leaves no stone unturned.”

Toomey contended that this flurry of official and unofficial support from Senators and the White House will not make a difference in the campaign, noting that Specter, as the longest serving Pennsylvania Senator since the chamber went to direct elections, is too well known a commodity.

“It’s of marginal value because Arlen Specter is very well known in Pennsylvania,’ Toomey said.

The winner of the GOP primary will take on Rep. Joe Hoeffel (D).

Public polling in the race has been sparse, although there are some signs of a potentially very tight race. A Keystone State Poll, run by G. Terry Madonna of Franklin & Marshall College, released Wednesday found Specter ahead 50-28 among registered Republicans but the sample of likely voters was too small to indicate how close the race was.

A mid-March poll conducted for the conservative Club for Growth showed Specter leading Toomey 47 percent to 37 percent.

A subsequent Quinnipiac University poll offered further evidence of Specter’s slippage, with his re-election percentage dipping to 36 percent in the latest survey. Specter led Toomey 45 percent to 29 percent in the same poll.

Both sides acknowledge that they expect the race to get closer as the primary approaches, and Specter’s camp is particularly worried that a low-turnout election could give Toomey a fighting chance.

“The momentum’s entirely on our side,” Toomey said.

The Congressman added that he was considering bringing in some of his endorsed supporters in the closing days of the campaign, including 11 current and former House Members.

While he has not had much backing of official Republican establishment in Washington or Pennsylvania, Toomey has relied on outside groups such as the Club for Growth to fuel his fundraising, making him at least marginally competitive with the better-funded incumbent. In addition to helping funnel contributions his way, the Club for Growth has run ads comparing Specter to Sen. John Kerry (Mass.), the Democratic presidential nominee-in-waiting.

Toomey has also won the support of conservative activists such as former presidential candidate Steve Forbes, former federal Judge Robert Bork and the American Conservative Union.

Specter is expected to have much more to spend in the race than Toomey. At the end of 2003, he held $9.2 million in his account, while Toomey had $2 million in the bank. It’s unclear, however, how much of Specter’s money is designated for the general election and off-limits for spending against Toomey — of McConnell’s $10,000, for example, only $5,000 can be spent in the primary.

Specter has used his surrogates for a dual purpose, rebutting Toomey’s attacks on the incumbent’s Republican credentials and for help in raising money.

Specter has taken in nearly $200,000 in contributions from his colleagues and local officials and ear-marked contributions they have steered his way: $59,000 from 13 current and former Members of Congress and nearly $17,000 from 35 local officeholders, according to an analysis of 2003 reports with the Federal Election Commission.

In addition, Senate Majority Leader Bill Frist (R-Tenn.) has steered $57,500 in conduit contributions from his supporters to Specter’s re-election through his leadership PAC. And Sens. John Warner (R-Va.) and Don Nickles (R-Okla.) used their Warner-Nickles Joint Committee to funnel $64,000 in contributions from their supporters to Specter.

Toomey’s support from his colleagues pales in comparison. He collected $15,500 last year from current and former Members, including conservative colleagues such as Reps. John Doolittle (R-Calif.), Pete Sessions (R-Texas), Jeff Flake (R-Ariz.), John Shadegg (R-Ariz.), J.D. Hayworth (R-Ariz.) and former Rep. Bob Barr (R-Ga.).

Doolittle, the Republican Conference Secretary, is the only member of House or Senate leadership to back Toomey, cutting a $1,000 check last year. Toomey’s taken less than $2,800 from local officials’ campaign accounts.

Former Sen. Phil Gramm (R-Tex.) was the only current or former Member in 2003 to give to both Specter and Toomey, $2,000 to each campaign.

This institutional support for Specter stands in stark contrast to the New Hampshire Senate primary of 2002, when then-Rep. John Sununu (R) successfully ousted the GOP incumbent, former Sen. Bob Smith, who had alienated many of his colleagues and given Sununu many inroads of support in the House and Senate.

As McConnell put it Wednesday, “We were divided on that one, we’re not on this one. We support Arlen enthusiastically.”