Democrats anticipating a final victory by Al Franken in the Minnesota Senate race could be poised to assume a level of power not seen for three decades after Sen. Arlen Specter of Pennsylvania rocked Washington on Tuesday by switching parties.

The defection by Specter, a 29-year Senate Republican, would give Democrats the 60 seats they need to overcome any GOP resistance -- if Franken becomes the next senator from Minnesota.

The Minnesota race is headed to the state Supreme Court, where Republican Norm Coleman is appealing this month's election-trial ruling, which found that Franken finished 312 votes ahead.

"The stakes have just gotten much higher," said Richard Hasen, an expert on election law at Loyola Law School in Los Angeles.

If Coleman's state Supreme Court appeal fails, Hasen added, "the pressure from national Republican leaders to appeal to the United States Supreme Court could be enormous."

While Specter's switch gives the GOP a much bigger incentive to continue the fight over the Minnesota seat, it could be that much harder for the Senate's 40 remaining Republicans to block Franken from being seated if he prevails before the state high court.

Specter's surprise move is itself a sign of the Republicans' deepening electoral troubles nationwide. Not since 1978 have the Democrats controlled the presidency and the U.S. House and held a supermajority in the Senate.

Neither the Franken nor the Coleman campaign had an immediate comment on the political effect of Specter's move.

"Senator-elect Franken looks forward to working with senators of both parties to make progress on President Obama's agenda and move our country forward," said Franken spokesman Andy Barr.

"We're just focusing right now on the appeal," said Coleman spokesman Tom Erickson, referring to legal briefs that are due Thursday at the Minnesota Supreme Court.

Erickson said Coleman was focusing on having the court count thousands of absentee ballots that the Republican contends were wrongly rejected.

Reaction to Specter

In Washington, Republican reaction to Specter's defection came fast and furious.

Republican National Committee Chairman Michael Steele said Specter was rude "to effectively flip the bird" to Senate Republicans, who were given little warning and will now have a harder time blocking Obama's expansive agenda on health care, energy and education.

But Specter, a 79-year-old cancer survivor, warned against the assumption that he will always agree with Democratic leaders.

"I will not be changing my own personal independence," Specter told Capitol reporters. "I will not be an automatic 60th vote."

Nevertheless, Specter was one of three Senate Republicans who voted for Obama's $787 billion economic stimulus package, the signature legislation of his first 100 days in office.

Sen. Amy Klobuchar, a Democrat who remains Minnesota's sole U.S. senator, said she got to know Specter when they worked together on Medicaid legislation last year. "I don't think he'll march in lockstep every step of the way," Klobuchar said. "But clearly, in general, he's supported the way the president is heading."

Leaders in both parties acknowledged that Specter's defection will alter the power equation in Congress.

"It highlights what's exactly at stake," said Jim Manley, spokesman for Sen. Harry Reid, D-Nev., the majority leader.

Sen. John Cornyn, R-Texas, who heads up the National Republican Senatorial Committee (NRSC), called Specter's switch a "disappointment" that creates a "potentially unbridled Democrat supermajority versus the system of checks and balances that Americans deserve."

Still, Republicans were eager to downplay the implications for Coleman, who could be the only thing standing between the Democrats and a Senate majority that is immune to filibuster -- the tactic by which a minority attempts to kill a bill through endless debate. It takes a 60-member majority to end such a debate in the Senate.

"Senator Specter's announcement today has no bearing on the Minnesota Senate race," said NRSC spokesman Brian Walsh. "In fact they could not be more different. The issue in Minnesota is about the fundamental principle that every vote should be counted and no voter should be disenfranchised. In contrast, Senator Specter's decision was not about principle, it was about political self-preservation."

Recent polls showed Specter, a centrist Republican, trailing former Rep. Patrick Toomey in a potential GOP primary in Pennsylvania next year. In explaining his decision to run in the Democratic primary in 2010, Specter said "the party has shifted very far to the right."

Democratic leaders acknowledged that they had been wooing Specter for months, promising to support his reelection if he runs as a Democrat.

No guarantees

Republican strategist Alex Conant, who worked on Coleman's 2002 Senate race, dismissed any notion that Specter's move will affect the Minnesota Republican's strategy in his legal standoff with Franken. "A senator's political posturing in Pennsylvania should not impact another senator's fight for fairness in Minnesota," he said.

Both sides emphasized that for now, Specter's decision changes nothing in Minnesota. "I understand that it may increase the intensity on both sides," Klobuchar said. "But remember, yesterday five [Minnesota Supreme Court] judges were deciding this, and today five judges are deciding this."

And while Franken, if he wins, would certainly be expected to be a more reliable Democratic vote than Specter, Democrats say there are no guarantees in politics.

"When we were at 58 or 59, I knew we would be able to gain some Republicans at some point, and lose some Democrats." Klobuchar said. "That's what happens here. So 60 is not always the magic number that it appears to be. But certainly it can be a rallying cry."

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