Published 12:23 p.m. ET -- Although stung by attacks from his former Republican colleagues in the Senate, Chuck Hagel is bracing to fight back against his critics and has no intention of withdrawing as the nominee to be Defense Secretary, according to the former senator's brother.
"He's not going to walk away from this," said Tom Hagel, who spoke to his older brother about the looming confirmation battle on Sunday night. "The way he's responding to this, he's just going to fight harder."
Tom Hagel's comments to NBC News came Monday just moments before Sen. Carl Levin (D-MI), chairman of the Senate Armed Services committee, announced the panel will vote Tuesday on Hagel's nomination.
White House spokesman Jay Carney responds to questions regarding Sen. Lindsay Graham's intention to fight the nomination of Chuck Hagel as defense secretary.
They also came amid mounting signs that some Republican senators are gearing up to try and fight it with a filibuster. On Sunday, South Carolina Sen. Lindsey Graham, a member of the committee, vowed to put a hold on the nomination -- as well as that of John Brennan to be CIA director -- if the administration does not provide more information about the attack on the U.S. consulate in Benghazi. Oklahoma Sen. James Inhofe, the ranking Republican on the Armed Services panel, said he was weighing a filibuster.
But other Republicans senators, including Arizona Sen. John McCain, Roy Blunt (R-MO), and Susan Collins (R-ME) -- have said they would not support a filibuster. It's not clear Graham would have the votes to go through with one.
There was also speculation the former Nebraska senator might pull his name as a result. Widely respected defense analyst Tom Ricks wrote Friday he believed there was a 50-50 chance Hagel would withdraw.
Tom Hagel, who served with his older brother in the Army during Vietnam and sat behind him during his rocky Jan. 31st confirmation hearing, described Chuck Hagel as "committed" and "optimistic" that he will be confirmed as Defense Secretary.
"I don't think there is any possibility" he will withdraw-unless he's asked to do so by President Obama, Tom Hagel said.
Chip Somodevilla / Getty Images
Former Senator Chuck Hagel testifies before the Senate Armed Services Committee during his confirmation hearing to become the next secretary of defense on Capitol Hill January 31, 2013 in Washington, DC.
The White House appeared to shoot down any hint of that Monday.
"We are absolutely committed to the Hagel nomination," said Tommy Vietor, a White House spokesman.
Tom Hagel said his brother was "shocked" by the level of personal animosity to his nomination from his former GOP colleagues in the Senate.
He also indicated that both he and his brother were upset about the blizzard of TV ads from anonymously funded advocacy groups attacking his nomination, calling the ads "absolutely gutless." He added, "If these people have integrity and believe in what they are doing, why don't they put their names to it?"
But while his brother was "tired" by the ordeal and it has taken a "personal toll," Tom Hagel said his brother was "ready to deal with it" and prepared "to respond to whatever attacks come out."