Senator Arlen Specter’s party switch is another blow to the already struggling Republican Party. It gives President Obama a greater chance of passing his legislative agenda. For the longer term, it is yet another warning that the Republican Party has become too Southern and too conservative, and that it is in danger of becoming a unified but small minority party.

The big news is that with the Specter switch and the likely seating of Al Franken in Minnesota, Democrats will have 60 votes in the Senate. No party has had more than 58 seats in the Senate since the 1970s. Sixty is often described as a magic number because 60 votes can overcome a filibuster. But while 60 votes is significant, it is not a drastic change from 58 or 59. Sixty Democrats may not unite on every cloture vote; Democrats such as Senators Ben Nelson or Arlen Specter may not vote to cut off debate. Conversely, the few remaining Republican moderates may vote with Democrats. Sixty is an impressive number for one party in the Senate, but on each cloture vote, Democrats will have to secure that supermajority to pass President Obama’s agenda. The more important point is that 60 seats is a big Democratic majority, and an extra vote from Specter on certain issues can only help the Democratic agenda.

While 60 is an impressive number for one party in the Senate, Democrats will have to secure that supermajority to pass Obama’s agenda.

How helpful will Specter be to Obama and congressional Democrats? Specter has vowed to remain an independent voice, a moderate Democrat who will buck his new party in certain areas. Issues where he is likely to be a thorn in the side of Democrats are those where he has already staked out a clear position; he will be reluctant to move. Take, for example, his opposition to the Employee Free Choice Act and to the nomination of Dawn Johnsen as head of the Justice Department’s Office of Legal Counsel.

But on a number of upcoming issues, Specter will likely vote with his new party. Just as Specter took votes for the Republican team, he will surely have to take them for the Democratic team. He is, after all, running on the Democratic ticket with the support of President Obama and congressional leaders. It is hard to imagine that he will cast the vote to bring down the president’s healthcare or climate change legislation and then run and win in a Pennsylvania Democratic primary.

As for the Republican Party, the switch is another example of the party losing its strength outside of the South. Consider Republicans’ predicament in the Senate. Republican moderates Olympia Snowe and Susan Collins hold Senate seats in Maine. But aside from this small GOP toehold, Republicans may be nearly shut out in the Senate in the Northeast and Midwest. Senators Judd Gregg and George Voinovich are retiring from their New Hampshire and Ohio seats, respectively. Democrats are favored to win in New Hampshire and the race in Ohio is even odds. If Republicans were to lose those seats in 2010, you could take a car trip from New Hampshire south all the way to Virginia without finding a Republican Senator. Or you could drive west passing through all of the Midwest to Minnesota and even on to North Dakota and Montana and you would find only Richard Lugar in Indiana. Again leaving out Maine, this group of 20 Northeastern and Midwestern states with 40 Senate seats would have Richard Lugar as its sole Republican Senator.

It is hard to imagine that Specter will cast the vote to bring down the president’s healthcare or climate change legislation and then run and win in a Pennsylvania Democratic primary.

That is an awfully blue map over a large geographic area. All is not doomed for Republicans, but it should be a wake-up call to recruit more serious moderate candidates in the near term. They have already recruited moderate former congressman Rob Simmons in Connecticut and a strong pragmatic conservative in Rob Portman in Ohio. But their odds would look better if they recruited Michael Castle to run for Senate in Delaware, Peter King in New York, Charlie Bass in New Hampshire, and Mark Kirk in Illinois. Even Pennsylvania might not be a lost cause for Republicans in 2010. Specter was right in his political analysis that he could not win in a Republican primary. Running as a Democrat, he has a clear shot to re-election. But there are potential pitfalls. He could get a serious Democratic primary challenge, especially if he strays from Democrats on key votes. Also, other Republicans, perhaps former Pennsylvania governor Tom Ridge, could jump in and give Specter a real race for his money in the general election.

Some conservatives have expressed relief that Specter is leaving the party. In their book, purity trumps victory. But in truth the real lesson of the defection of Specter is that the party needs to recruit more moderate Republicans, more Arlen Specters, to run for the Senate—and soon, before the map turns even bluer.

John C. Fortier is a research fellow at the American Enterprise Institute.

FURTHER READING: Fortier recently wrote about how Republicans should increase their appeal among moderates and non-Southerners.

Image by Darren Wamboldt/The Bergman Group.