Five-term Republican Sen. Arlen Specter said Tuesday that he is switching parties and will run next year as a Democrat, substantially eroding Republicans’ power in Washington and repositioning himself to ride his popularity among Pennsylvania Democrats to re-election in 2010.
Although he looked at the polls and realized he couldn’t win re-election as a Republican, Mr. Specter said, the Republican Party had “moved far to the right” and he now finds his political philosophy “more in line with Democrats.”
Democrats have cheered Mr. Specter for challenging Republican stances on Capitol Hill.
“I have been a Republican since 1966,” Mr. Specter said. “I have been working extremely hard for the party, for its candidates and for the ideals of a Republican Party whose tent is big enough to welcome diverse points of view. While I have been comfortable being a Republican, my party has not defined who I am. I have taken each issue one at a time and have exercised independent judgment to do what I thought was best for Pennsylvania and the nation.”
His switch, the result of months of lobbying by Democrats, including Vice President Joseph R. Biden Jr., gives the Democratic caucus 59 seats, including two independents, in the Senate. The total is one shy of the number needed to prevent Republicans from being able to filibuster.
The move will only intensify the brutal legal battle in Minnesota, where Democrat Al Franken leads Sen. Norm Coleman in the ballot count from November’s election. Mr. Coleman is pursuing legal challenges to the count.
Republicans’ reaction ranged from disappointment to outrage - their Senate campaign committee sent out a fundraising e-mail Tuesday with the subject line “Good riddance.”
It was not clear whether the switch will matter much for the congressional agenda this year. Mr. Specter said he won’t reflexively vote in line with the Democratic Party, and he listed one of President Obama’s nominees and a union-backed bill as two issued on which he will still oppose the White House.
“On some very partisan issues, it may hurt us,” said House Minority Leader John A. Boehner, Ohio Republican, though he said there are “a dozen Democrats to the right of Specter as it was.”
“I’m not sure it’s going to be a net negative at the end of the day,” he said.
Mr. Specter, 79, said he decided to leave the Republican Party this weekend after internal poll results showed Friday that he had no chance of re-election as a Republican.
Public polls in Pennsylvania showed him trailing badly to Pat Toomey in the Republican primary next year. Mr. Specter barely beat Mr. Toomey in a 2004 primary.
Mr. Specter’s approval rating among Democrats is 71 percent, and strategists and pollsters said the senator is simply following his supporters.
“When he found out he wasn’t winning among Republicans, Specter not only took his ball and went home, he joined the other team,” said Pittsburgh-based Republican campaign adviser John Brabender.
While acknowledging that his switch might not change much substantively, Democrats welcomed Mr. Specter’s move as a sign of Republican trouble. Mr. Specter said he has the commitment of Democratic leaders, including Mr. Obama, to support him in next year’s election, though Sen. Bob Casey, Pennsylvania Democrat, would not go that far.
“I am not going to get into 2010 discussions. I just think it’s premature today,” he said. “We’re very happy about this. But I’m not going to answer any questions about support.”
Democrats have agreed to give Mr. Specter the seniority that he would have had if he’d been a Democrat since his first election in 1980. He will not gain control of the Senate Judiciary Committee, on which he was the top Republican, but he said other chairmanships such as an Appropriations Committee slot have to be worked out.
Republican National Committee Chairman Michael S. Steele said the party will work to defeat Mr. Specter in next year’s general election.
“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,” Mr. Steele said. “Republicans look forward to beating Senator Specter in 2010, assuming the Democrats don’t do it first.”
The switch is a major coup for Senate Majority Leader Harry Reid, Nevada Democrat, who had been talking with Mr. Specter for months about switching parties.
A month ago, Mr. Reid told reporters that a move seemed unlikely after Mr. Specter announced that he would oppose a union-backed bill known as card-check, which would make it easier for unions to organize in the workplace. But on Tuesday, Mr. Reid said Mr. Specter’s bipartisan approach is welcome.
Mr. Specter has been both a critical ally and an impossible roadblock for his party.
Earlier this year, he and two other Republican senators voted to support Mr. Obama’s stimulus spending bill, enraging conservatives.
But as chairman of the Judiciary Committee, he helped shepherd Chief Justice John G. Roberts Jr. and Supreme Court Justice Samuel A. Alito Jr. through the confirmation process.
American Conservative Union Chairman David A. Keene called Mr. Specter a “sometimes ally.”
“Arlen and I have been personal friends and sometime allies for more than 20 years,” said Mr. Keene, who said that without Mr. Specter, conservatives might not have received key judicial picks. “We might well be paying higher taxes and our Second Amendment rights would have been in greater jeopardy than has been the case during his years in the Senate.”
In a press conference Tuesday Mr. Specter was particularly critical of the Club for Growth, a conservative group that funds primary challengers to moderate Republicans. Mr. Toomey, his primary opponent in 2004, ran the group from 2005 until earlier this year when he stepped down to challenge Mr. Specter.
Mr. Specter said Republicans should fight against the club.
“Republicans didn’t rally to Wayne Gilchrest in Maryland. He was beaten by the Club For Growth on the far right. They lost the general election. … Republicans didn’t rally to Heather Wilson in New Mexico last year and she was beaten in a primary and lost in the general election,” he said.
He said the club backed a primary opponent to Sen. Lincoln Chafee, Rhode Island Republican, in 2006, weakening Mr. Chafee and allowing a Democrat to beat him in the general election. Mr. Specter said that flipped control of the chamber to Democrats and allowed Democrats to block 34 of President George W. Bush’s federal judicial nominees.
“For the people who are Republicans that just sit by and allow them to continue to dominate the party after they beat Chafee, cost us the Republican control of the Senate and cost us 34 federal judges, there ought to be a rebellion. There ought to be an uprising,” he said.
Chris Chocola, the new president of the club, said Mr. Specter showed “how unprincipled he is.” Mr. Chocola said the club will now redouble its efforts to defeat Mr. Specter.
Moderate Republicans expressed disappointment in Mr. Specter’s move.
“That’s not something I would ever consider doing,” said Sen. Susan Collins, Maine Republican. “But I do think that our party needs to make clear that centrists are welcome, and sometimes that message is not sent as clearly as it should be.”
The last time a party held a filibuster-proof majority was in 1977 and 1978, when Democrats held 61 seats.
Mr. Specter’s change could mark the second time this decade that Republicans have been undercut by a party switch. James M. Jeffords’ switch from Republican to independent in 2001 gave Democrats a majority in the chamber.
• Kara Rowland, Donald Lambro and Ralph Z. Hallow contributed to this report.