A couple of weeks ago I wrote the following with regards to the reelection hopes of Arlen Specter, the Pennsylvania Senator facing a potentially overwhelming Republican primary challenge by former Congressman Pat Toomey:

[T]he only way Specter wins another term (and it's hard for me to envisioning him not wanting this) is if he leaves the Republican Party (though not necessarily the Republican caucus) and calls himself and independent for 2010.

It looks like Specter is thinking along similar lines:

Sen. Arlen Specter said Tuesday that he will not run for reelection in 2010 as a Democrat, but might run as an Independent.

[...]

"I'm staying a Republican because I think I have a more important role to play there," he said. "I think the United States very desperately needs a two-party system. ... And I'm afraid that we're becoming a one-party system, with Republicans becoming just a regional party."

At the same time, Specter said he is open to the possibility of running as an Independent with the understanding that he would caucus with Republicans, just as Sen. Joe Lieberman (I-Conn.) did with Democrats in 2006.

Though he left that option on the table, he suggested it would be a last resort.

While the Democrats would like to see another member added to their ranks in the Senate by way of a Specter defection -- a situation I never saw happening -- this news could still actually bode well for the Democrats. Here's how it plays out, as I wrote earlier this month:

In a three-way race against Toomey and a Democrat, Specter wouldn't have to carry a majority of Republican primary voters, or indeed even a majority of Republicans overall. Instead, he would only have to pull in perhaps a third or so of Republicans, as well as a good chunk of independents and Democrats (which he has fairly consistently done). In such a scenario, Specter would be freed up to vote on measures like the Employee Free Choice Act, among others, as he would be competing not only for the votes of conservatives but also the votes of moderates and liberals.

If Toomey moves forward with his run, I fully expect Specter to leave the Republican Party -- though not the Senate Republican caucus -- and declare for reelection as an Independent. And, frankly, if Specter played his cards right (particularly on EFCA,w here he could pick up the support of big labor), he'd be more likely than not to win a sixth term. The big remaining question, though, would be whether the Senate GOP would be able to withstand the heat from the base allowing Specter to stay among their ranks, keeping his seniority. All in all, this should be a heck of a Senate contest.