(CNN) - Now that Chuck Hagel has been nominated for defense secretary, the former Republican senator from Nebraska faces what many expect to be an uphill battle for confirmation in the Senate.
Hagel took quite a pounding from some senators and independent groups on both sides of the aisle in the days before last week's announcement, with many of them taking issue with some of Hagel's positions and comments dealing with Iran, Iraq and Israel in particular.
But Republican Sen. Bob Corker of Tennessee raised a new issue Sunday, warning that another concern might be Hagel's "overall temperament." Corker questioned whether he's "suited to run a department or a big agency or a big entity like the Pentagon."
"There are numbers of staffers who are coming forth now, just talking about the way he has dealt with them," Corker said on ABC's "This Week."
Corker added he'll be meeting with Hagel next week and has an "open mind" about the process but cautioned he still has many questions.
Critics have also attacked Hagel for opposing the troop surge in Iraq and making comments referring to the "Jewish lobby," prompting some to accuse Hagel of anti-Semitism.
Hagel has attempted to set the record straight in the media and in conversations with Pentagon staffers. In particular, he has said those who criticize him for opposing unilateral sanctions against Iran have distorted the message.
"I have not supported unilateral sanctions because when it is us alone, they don't work and they just isolate the United States," he told the Lincoln (Nebraska) Journal Star last week.
Sen. John McCain, who also served with Hagel in the Senate, has been a staunch critic of the nomination. Asked by CNN Sunday what questions he has for his former colleague, McCain said he is interested in Hagel's "view of America's role in the world."
"There will be a number of questions that we have (about) some of his statements in the past concerning, for example, that the surge in Iraq would be the greatest blunder since the Vietnam War, which is clearly a bizarre statement," he said. "We'll be asking questions and we'll be reserving judgment."
Pressed on whether he'd try to block the nomination, McCain said "no."
"I plan to make a judgment as to whether I think he's appropriate to be secretary of defense or not," he continued.
Democratic Sen. Richard Blumenthal of Connecticut said that while he's not "comfortable" with some of the statements Hagel has made in the past, he plans to ask questions during the hearings and predicts that Hagel will be confirmed.
"I think Senator Hagel will be approved. I think the history of nominees shows, and I think his own qualifications also demonstrate, that he has the capacity. But I want to know his positions on those issues. And I reserve judgment until I hear his responses," Blumenthal said on "Fox News Sunday."
On the same program, Republican Sen. Kelly Ayotte of New Hampshire said she was "perplexed" at the president's choice.
"I think it's fair to say that if you look at his prior positions, that he has a lot of questions to answer," she said. "And, I'm deeply troubled by it. I guess I also wonder what message are we sending to Iran, what message are we sending to Israel?"
However, Hagel had a big ally Sunday in Sen. Jack Reed of Rhode Island, who argued Hagel is "very capable of explaining (his) positions."
"I think he brings some unique quality to this job. He is someone who has been involved in issues of national security as a United States senator," Reed said on ABC. "But I think one thing that's terribly compelling - and it goes to his credibility with the forces - he's been a combat soldier. He's fought. He has literally walked in their boots. That, I think, will inspire great confidence in the military officers and enlisted men that he deals with, and women."
Hagel also got a boost from former Secretary of State Colin Powell, who said Sunday that Hagel would be an excellent fit for defense secretary because of his military service in Vietnam, where Hagel was wounded twice. He was awarded two Purple Hearts.
"I will tell you who thinks that makes him a good candidate for secretary of defense: the men and women in the armed forces of the United States, who know that this is a guy who will be very careful about putting their lives at risk, because he put his life at risk," Powell said on NBC's "Meet The Press."
But Powell said it takes more than just combat experience to be a good defense secretary. He said Hagel has the right pragmatic worldview to fit the role.
"He knows what war is, and he will fight a war if it's necessary, but he's a guy who will do it with great deliberation and care," Powell said.
- CNN's Gregory Wallace and Greg Clary contributed to this report.