15 GOP senators to Obama: Withdraw Hagel's nomination

This post was updated at 2:37 p.m. ET.

President Obama should withdraw Chuck Hagel's nomination to be the next defense secretary, 15 Republican senators argued today in a letter to the White House.

The letter was signed by Sens. John Cornyn, R-Texas; James Inhofe, R-Okla.; Lindsey Graham, R-S.C.; Roger Wicker, R-Miss.; David Vitter, R-La.; Ted Cruz, R-Texas; Mike Lee, R-Utah; Pat Toomey, R-Pa.; Marco Rubio, R-Fla.; Dan Coats, R-Ind., Ron Johnson, R-Wis.; Jim Risch, R-Idaho; John Barrasso, R-Wyo., Tom Coburn, R-Okla, and Tim Scott, R-S.C..

In it, the senators argue that it would be "unprecedented" to confirm a nominee who did not have a "broad bipartisan base of support."

"The occupant of this critical office should be someone whose candidacy is neither controversial nor divisive," they write.

And in light of Hagel's "deeply concerning" performance at his confirmation hearing that raised "serious doubts about his basic competence," the senators conclude that Hagel's nomination must not move forward.

They raise particular concerns about Hagel's "seeming ambivalence" about halting Iran's pursuit of a nuclear weapon, worrying that "If Senator Hagel becomes Secretary of Defense, the military option" to prevent an Iranian nuke "will have near zero credibility."

The White House pushed back on Thursday, with White House press secretary Jay Carney saying Hagel would "absolutely not" be withdrawn from consideration, labeling the foot-dragging on Hagel's nomination "political gamesmanship."

Any suggestion that Hagel might withdraw, Carney said, "might have been found in the minutes of the meetings of the Friends of Hamas," joking about a fictitious group to which Hagel was erroneously linked last week by a right-wing website.

It is not clear what - if any - impact the letter will have on the political calculus of the president, who has signaled that he intends to push Hagel's nomination through the Senate, come what may.

But it hasn't been easy. Last week, for the first time in history, Republicans delayed a vote on a defense secretary nominee by requiring a 60-vote majority for the nomination to proceed. Democrats were unable to clear the 60 vote threshold - the 55 in their caucus were joined by only 4 Republican senators.

• Senate GOP filibusters Hagel confirmation
• Amid objections, Hagel clears first hurdle to confirmation

Several of the Republicans who voted to delay the nomination signaled that, while they might not ultimately vote to confirm Hagel, they would eventually allow his nomination to move to the floor for final approval, which requires only 51 votes to confirm Hagel. Many said they simply needed more time to consider a nomination of such consequence.

Congress is in recess this week, but Senate Majority Leader Harry Reid, D-Nev., has scheduled another confirmation vote in the Senate next week. And in an encouraging sign for Hagel and the White House, Sen. Richard Shelby, R-Ala., told the Decatur Daily yesterday that he will support Hagel's nomination when Congress returns from recess. "He's probably as good as we're going to get," Shelby said.

Shelby joins two other Republicans - Sens. Thad Cochran, R-Miss., and Mike Johanns, R-Neb. - who have indicated they would vote to confirm Hagel.