Texas Senator John Cornyn, Chairman of the National Republican Senatorial Committee, has weighed in on the impending Toomey vs. Specter 2010 showdown and sided with the incumbent. In a letter to Pennsylvania Republicans, Cornyn said that it would be easier for the GOP to make gains in the Senate with Specter on the ticket.

As I survey the political landscape of the upcoming 2010 elections, it’s clear we need more candidates that fit their states. While I doubt Arlen could win an election in my home state of Texas, I am certain that I could not get elected in Pennsylvania. I believe that Senator Specter is our best bet to keep this Senate seat in the GOP column. A vote for Arlen Specter is a vote for denying Harry Reid and the Democrats a filibuster-proof Senate.

Toomey mentioned in his letter of resignation from the Club for Growth yesterday that Specter’s support of pieces of the Democrat agenda is exactly what he believes we do not need in the Senate right now.

With 41 Republican senators, we should be able to use the filibuster to stop them in their tracks. But several of those Republicans support that liberal agenda. One of them is Arlen Specter.

In his letter to Pennsylvania Republicans, Senator Cornyn makes the argument that the GOP must focus its resources where they are the most important, growing the party by defeating vulnerable Democrats.

The political math for Republicans in 2010 is tough. We must defend 19 of our Senate seats — six of which are in states (such as Pennsylvania) won by President Obama. The Democrats have to defend just 17 of their 59 seats, only two of which are in states Senator McCain won. With just 41 Members in the Senate Republican Conference, it’s vital that we focus our limited resources on growing the party and beating Democrats.

Not by coincidence I imagine, Cornyn’s letter was dated March 26, just one day after a Quinnipiac poll showed Specter trailing Toomey by 14 points.

Specter is already on the defensive against Toomey, using a recent appearance on MSBC’s Morning Joe to try and paint Toomey as an out of touch conservative extremist.

Specter said Toomey fought for deregulation, embraced private accounts in Social Security and, if nominated, would lose the general election and allow Democrats to pass so-called card-check legislation favored by organized labor.

Specter said Toomey is “to the right” of former Sen. Rick Santorum (R-Pa.), adding, “Santorum lost by 18 points [in 2006], spent $31 million and was a two-term incumbent.”

Of course in 2007 Specter was a supporter of the Democrat’s card check legislation. Under pressure from groups like Toomey’s Club for Growth and others, Specter recently switched his stance. Specter and Cornyn make the argument that Pennsylvania’s senior Senator would be better for the general election, but organized labor, who may have backed him before his chard check flip flop, is furious at his recent decision.

An excerpt from a statement by AFL-CIO President John Sweeney:

Today’s announcement by Sen. Specter – a sponsor of the original Employee Free Choice Act who voted for cloture in 2007 – is frankly a disappointment and a rebuke to working people, to his own constituents in Pennsylvania and working families around the country.

Vice President Biden and Majority Leader Harry Reid were working to get Specter to switch parties, an effort halted after Specter rejected the union backed bill.

Senate Majority Leader Harry Reid (D-Nev.) said Friday that Sen. Arlen Specter’s (R-Pa.) decision to reject “card-check” legislation has ended any chance of a party switch.

Reid as well as Vice President Biden, Pennsylvania Gov. Ed Rendell (D) and Sen. Bob Casey Jr. (D-Pa.) have tried recently to persuade Specter to leave the GOP.

Toomey believes that Pennsylvania Republicans are clamoring for a Senator who doesn’t flip flop so easily and hasn’t considered abandoning their party to play nice with the Democrat majority.

Specter might believe you have to be a liberal like him in order to win in Pennsylvania, but I do not share that view, nor do most Pennsylvania Republicans.

One thing is sure, the endorsement of Specter by the NRSC will only add fuel to the fire of what might be the most interesting 2010 GOP Republican Senate primary race. Toomey will undoubtedly use it to paint Specter as the choice of the Washington elite and not the home grown representative that Pennsylvanians need in the US Senate.