The president’s nominee to become the next Defense secretary is already facing tough opposition from a wing of the Republican Party, in part over differences regarding the application of military power, but former Republican Sen. Chuck Hagel has a long record of being hawkish when it comes to defense policy and spending.

“Chuck Hagel is the leader that our troops deserve,” President Barack Obama said Monday in announcing the nomination. Obama also tapped John O. Brennan, the top White House counterterrorism adviser, to run the CIA. If both are confirmed, a combat veteran would be in charge of the Pentagon and a longtime CIA officer would be at the helm of the spy agency.

Throughout his 12-year Senate career, Hagel was a strong supporter of the military, routinely voting to support defense policy bills and spending bills. The Nebraska lawmaker also voted to expand warrantless wiretapping and the 2001 law to bolster law enforcement powers to fight terrorism known as the Patriot Act (PL 107-56). He supported controversial President George W. Bush administration nominations, including Michael B. Mukasey to become attorney general in 2007 and John R. Bolton to be U.S. ambassador to the United Nations in 2005.

But for several weeks, ever since word of Hagel’s possible nomination surfaced, the neoconservative wing of the Republican Party has excoriated the former senator for his views on Israel and Iran. Some also have raised concerns about his willingness to reduce the size of the Pentagon.

Indeed, some, such as Sen. John McCain of Arizona, have suggested that Hagel is a Republican in name only.

These attacks have left some leading voices in the GOP nonplussed, and there are indications that key Republicans are willing to give Hagel a chance to make his case.

“I don’t understand why the neocons are so upset,” said Brent Scowcroft, a former national security adviser to President George H.W. Bush who now runs a consulting firm, the Scowcroft Group. “One thing I like about him is he is a sound, solid thinker who comes to his own conclusions. He’s not knee-jerk. If Israel does something the United State supports, he supports Israel. If Israel does something we don’t support, he doesn’t support Israel. Israel is just another country to him. I don’t think he is anti-Israel.”

A Reliable Republican Vote

From 2001 to 2006, Hagel voted, on average, 95 percent of the time with President George W. Bush and with his party 92 percent of the time, according to CQ Roll Call’s vote studies.

Democrats are quick to point out that Hagel also is a decorated war veteran, and he would be the first Vietnam veteran and noncommissioned officer to serve as Defense secretary.

“On the Appropriations Committee, those of us charged with handling the Senate’s work on the Pentagon budget will have to make more than a hundred billion dollars in cuts to begin with, and it will be good to work with someone like Chuck Hagel who can lead the Pentagon during a difficult time of transition,” said Sen. Patrick J. Leahy, D-Vt., a senior leader on Appropriations.

But Hagel has piqued the ire of neoconservatives for opposing controversial CIA interrogation techniques, the use of the military’s Guantánamo Bay, Cuba, detention facility for terrorist detainees and the Iraq War, after initially supporting it.

“He’s clearly alienated some Republicans over that and time has passed and the concerns are going to be from here on out,” said Dov S. Zakheim, who served as undersecretary of Defense in the George W. Bush administration. “He’s a strong believer in saying what he thinks. You can’t criticize him for that. You can disagree with him.”

Not surprisingly, in 2007, with Hagel in full-throated opposition to the war in Iraq, his presidential and party unity vote percentages dipped into the low 70s.

Hagel has also been criticized for his past statements supporting engagement with Iran and groups such as Hezbollah, rather than applying sanctions. He opposed Bush’s surge of troops into Iraq and Obama’s later surge in Afghanistan.

“As you know, Chuck Hagel and I had some differences over the years, for example, over the surge, which he said would be the worst mistake since the Vietnam War, and obviously it was successful,” McCain said in a late-December interview on CNN.

But Scowcroft said he, too, opposed the Iraq War, “and I don’t think there are too many supporters of it now.” Indeed, he argued that Hagel is thoughtful and patient. He said within every presidential administration there are those who become frustrated with the slow nature of diplomacy.

With Hagel, Scowcroft said, because of his combat experience, he will question the implications of military intervention.

“I think he’s particularly good on one element: our involvement militarily around the world,” he said. “He’s been in the foxhole and from my own experience, when a crisis comes up and it is complicated and diplomacy seems awkward and difficult, there is always a call to say cut through all this stuff with the military, like Iran, like Iraq. ‘Let’s just take care of it.’

“He will have a visceral answer to that. What will he get into if we do that? It’s not high policy. It is what does it mean when you get involved militarily in a conflict?”

Military Cuts

While Hagel has been a reliable Pentagon backer in the past, he has expressed support in recent years for reducing the size of the Pentagon. Zakheim said some members of the Republican Party are uneasy with his views.

“The Defense Department, I think in many ways, has been bloated,” Hagel told the Financial Times in 2011. “So I think the Pentagon needs to be pared down. I don’t think our military has really looked at themselves strategically, critically, in a long, long time.”

His comments will likely be revisited during his upcoming Senate confirmation hearing, particularly as the department he would lead girds for the possibility of across-the-board cuts that Defense Secretary Leon E. Panetta has labeled catastrophic and devastating for the military.

Hagel’s views may not necessarily be a negative to all members of the GOP.

“He’s clearly been critical of the size of the Pentagon,” Zakheim said. “There are many Republicans who believe the acquisition needs reforming; some compensation elements need reform; defense, health care and retirement need reforming.”

Zakheim said much will depend on what Hagel tells the Senate Armed Services Committee and senators in private. “Let’s face it, he is part of the club; he’s been a senator for many years,” Zakheim said. “I can’t think of anyone, other than John Tower, who didn’t make it through who was a senator himself.”

Megan Scully contributed to this report.