Republican National Committee Chairman Michael Steele suggested that Arlen Specter did the party a service by leaving. Steele may be right, but not in the way he intended when he derided Specter on ideological grounds.

"Let's be honest," Steele said Tuesday. "Senator Specter didn't leave the GOP based on principles of any kind. He left to further his personal political interests because he knew that he was going to lose a Republican primary due to his left-wing voting record."

"Republicans look forward to beating Senator Specter in 2010, assuming the Democrats don't do it first," he said.

He may as well have said: Don't let the door hit you on the way out.

No doubt the comments played well to the base, which according to recent polling is at an all-time low. An ABC/Washington Post survey released this week indicated that just 21 percent of voters describe themselves as Republican - down from 29 percent at this time last year. That's the lowest figure garnered in an ABC/Post poll over the last 25 years.

Too bad Steele and others with a responsibility to advance the party didn't embrace Specter after the 2008 presidential election as the embodiment of the sensible Republican politics needed to offset heavy voter-registration (and electoral) losses.

Instead, the GOP allowed its message to be corrupted by individuals seeking to advance a conservative, not necessarily Republican, message. These are the same people still fixated on things like the president's middle name and whether the abortion politics of Health and Human Services Secretary Kathleen Sebelius should have precluded her appointment despite the outbreak of swine flu.

Instead, they have laid the groundwork for Specter to do as a party outsider what he wanted to do as an insider. By leaving, he may have just initiated the GOP moderation he long desired.

Here's how.

Pat Toomey cannot defeat Arlen Specter in a general election. The state Democratic Party's registration advantage is now 1.2 million. More than 200,000 Republicans jumped ship last year alone.

Who were those converts? According to a Muhlenberg College Institute of Public Opinion poll of 400 Pennsylvania Republicans who defected in 2007 and 2008, a combined 64 percent described themselves as moderate or liberal. Two-thirds said they favored abortion rights. Thirty-eight percent said their views on social issues - gay marriage or abortion - were closer to those espoused by the Democrats. Fifty-three percent described the GOP as "too extreme in its positions."

In short, they were the moderate suburbanites who have been supporting Specter for three decades. They, like Specter, have moved on. As longtime Philadelphia political operative Ken Smukler told me last week, the only things left under the Republican tent are the elephants.

Whereas Specter was always vulnerable to a challenge from a more conservative candidate in a primary election, now he is vulnerable in a general election between centrists. Toomey is too conservative to win a general election - just consider what happened to Sen. Rick Santorum in 2006.

But another Republican could make things interesting: Tom Ridge.

Think about it. He's Central Casting handsome, public-housing raised, Harvard educated, a Vietnam veteran, and former congressman, governor, and secretary of Homeland Security. This is senatorial timbre. He should have been vice presidential timbre. John McCain knew that. According to reports published last fall, McCain wanted to choose Ridge or Joe Lieberman as his running mate - and still hoped he'd be able to do so just days before introducing the country to Sarah Palin.

And with that announcement, McCain sold out to the ideologues of the GOP, who rejected Ridge because he favored abortion rights - an attribute that should have ensured his selection, not ruled it out.

Ridge's rejection was a perfect example of a Republican Party content to bind itself to litmus tests at a time when the party should be seeking to attract - or at the very least tolerate - the politics of guys like Tom Ridge and Arlen Specter.

Could Ridge defeat Toomey in a primary? Yes. His Vietnam record and antiterrorism role could be sold to the same Pennsylvania conservatives who were lying in wait to vote against Specter. The folks who, according to political observer Larry Ceisler, wanted to put Specter "in front of a GOP firing squad and tell him, 'Please don't move.' " Ridge would be well-regarded by this group because he is not Arlen Specter.

How ironic it would be for Specter to leave the GOP because of its unwillingness to moderate, only to see the GOP be led by a centrist. Even if Specter were to lose the battle royal that could result with Ridge, he would have done an enormous public service to the GOP.

Michael Smerconish's column appears Thursdays in the Philadelphia Daily News and Sundays in Currents. He can be heard from 5 to 9 a.m. weekdays on "The Big Talker," WPHT-AM (1210). Contact him via www.mastalk.com.