Why am I not surprised that Sen. Arlen Specter won the Pennsylvania Republican Senate primary on Tuesday?

Specter used a massive campaign war chest, endorsements from President Bush and Sen. Rick Santorum (R-Pa.) and his own aggressive campaigning to eke out a narrow win over Rep. Pat Toomey, a three-term Congressman who complained that Specter is too liberal.

The race was as close as late polls predicted it would be, and Toomey can take pleasure in knowing that he almost upset a Pennsylvania institution. But this is politics, not horseshoes, and coming close isn’t a goal to which most politicians aspire.

There were plenty of winners and losers, both in and out of the Keystone State. Specter, of course, was the biggest winner. With late polls showing the race closing, some insiders were starting to write off the four-term Republican’s chances. But Specter would not be denied.

Winners

President Bush. The president and vice president were all over Specter’s direct mail, and Bush put his reputation on the line with a late trip into the state on Specter’s behalf. With Toomey attacking Specter as not sufficiently conservative, Bush was a “Good Housekeeping Seal of Approval” for some GOP voters still unsure about the Senator after 24 years.

Sen. Rick Santorum. He took a huge gamble in this race, supporting Specter even though the former Philadelphia district attorney is one of his party’s least conservative Senators. Santorum traveled the state with Specter in the primary’s final days, and his endorsement, like the president’s, almost certainly persuaded crucial conservatives to back Specter.

Republican Main Street Partnership. The centrist group has been trying to establish itself as a moderate counterweight to the Club for Growth, and the group’s very visible support for Specter should enhance its reputation and fundraising ability.

Niccolo Machiavelli. “It is far safer to be feared than loved,” wrote Machiavelli in his 16th century work “The Prince,” and it’s hard to find a better example than Specter, who is certainly feared more than he is loved.

GOP Sens. Bill Frist (Tenn.) and George Allen (Va.). The Senate Majority Leader and the chairman of the National Republican Senatorial Committee have to be breathing a sigh of relief. Not only did they back Specter, but GOP prospects in the fall would have been iffier without him on the ballot.

Survey USA. I can’t believe I’m writing this, but Survey USA polling, which I’ve criticized strongly in the past, was dead-on in projecting a statistical dead heat. I remain skeptical of automated telephone polls, but I also can’t ignore Survey USA’s success in this race.

Losers

Club for Growth. The anti-tax group put about $2 million into the Senate race to defeat Specter, and they came up short. They deserve some credit for Toomey’s strong showing, but if you challenge the King, you had better kill him. They didn’t.

Rep. Joe Hoeffel. He officially became the Democratic Senate nominee this week, but he would have much rather faced Toomey than Specter. Hoeffel’s fundraising hasn’t been impressive, and he needed a boost of Democratic optimism about this race — and a more ideological target — to jump-start his Senate bid.

The Democratic Senatorial Campaign Committee. You have to hand it to the DSCC. They are in spin mode 24/7, even if their analysis in this case is about as credible as a Jayson Blair article. And once lost, credibility is hard to recover.

Ninety minutes before the polls closed, the DSCC sent out an e-mail titled “Pennsylvania: Dems Win Tonight in PA Regardless of Outcome.” Shortly after midnight, another release crowed, “Specter Squeaker Puts PA Firmly in Play for Democrats as Voters Look For Change.” Instead of the general being a toss-up — as a Hoeffel-Toomey race would have been — it becomes a likely GOP retention.

Winner & Loser

Montgomery County, Pa. By now, it should not be news that GOP strength in the Keystone State has been moving west, away from Southeastern Pennsylvania and toward Pittsburgh. Former Gov. Tom Ridge hails from Erie, Sen. Rick Santorum is from the Pittsburgh area, and former Gov. Dick Thornburgh and 2002 GOP gubernatorial nominee Mike Fisher are also from Western Pennsylvania.

But Montgomery County provided virtually all of Specter’s statewide margin of victory, reviving — possibly for the last time — its traditional role as a bastion of moderate Republican clout.

Or maybe not. At the same time that Specter was winning, the winner of the primary to be the Republican nominee for state attorney general this year was Tom Corbett. Corbett, a former U.S. attorney for Western Pennsylvania, beat Bruce Castor, the Montgomery County DA.