(FILE PHOTO) In this composite image a comparison has been made between US President Barack Obama (L) and Chuck Hagel.
STORY HIGHLIGHTS
- Officials say Obama will nominate former Sen. Chuck Hagel as defense secretary
- Several GOP lawmakers voicing staunch opposition to his nomination
- Hagel has taken controversial positions on several issues that could be on his plate
(CNN) -- He forged his views of war and the military as a young man in mine-plagued fields of Vietnam. Now Chuck Hagel may become the first Vietnam veteran and first enlisted soldier to serve as U.S. defense secretary.
But the road from his nomination, which President Barack Obama will announce on Monday, to confirmation is packed with obstacles -- political landmines that could derail the effort.
In choosing this Republican to take over for outgoing Defense Secretary Leon Panetta at the Pentagon, Obama ignited controversy and anger among many of the Republicans who will be poised to grill him.
"Let's just say if Chuck Hagel is nominated," CNN Chief Political Correspondent Candy Crowley said Sunday, "set your TiVo for the hearings."
Some of flashpoints that his critics point to are the same ones that his vocal supporters like.
Hagel has said he favored U.S. negotiations with Iran and opposed increased sanctions. He has supported Israel entering negotiations with Hamas, though also insisted Hamas end terrorism and accept Israel's right to exist.
And the former U.S. senator from Nebraska has criticized U.S. policy on Afghanistan, including a 2009 "surge" that sent in 30,000 additional troops. If he becomes defense secretary, Hagel will face the challenge of ending that U.S.-led war and overseeing a smaller training force in the country.
But the controversies surrounding Hagel aren't just about his policy positions. They're also about his views.
Some are bothered by a comment he made in 1998 about an ambassadorial candidate being "aggressively gay" -- which he recently apologized for. And in a 2007 interview, he said a "Jewish lobby intimidated lawmakers" -- sparking heated criticism. A rabbi in Hagel's home state insists he is "a friend of Israel."
Sen. Lindsey Graham, R-South Carolina, told CNN he believes that if confirmed, Hagel "would be the most antagonistic secretary of defense towards the state of Israel in our nation's history."
Sen. Chris Murphy, a freshman Democrat from Connecticut, said that he believes "Republicans are spoiling for a fight."
The rhetoric over Hagel on both sides is ratcheting up.
Past controversies have led presidents to pull some nominations. But the bumpy road ahead is unlikely to faze the 66-year-old at the center of it all.
"Chuck Hagel is not afraid of challenge -- or risk," his biographer, Charlyne Berens, wrote in 2006.
'All I can to prevent war'
If he becomes defense secretary, Hagel will be tasked with carrying out the orders of a president who vowed to end two wars -- Iraq and Afghanistan.
Ending and avoiding war are part of what he committed his life to while in his 20s in Vietnam, Berens writes.
"After a year of Vietnam's miserable heat, nearly constant danger, and violent campaigns like the Tet Offensive, Chuck Hagel came back to the United States ready to get on with things -- and with both a loyalty to the U.S. military and a belief he should do all he could to prevent his nation's being involved in another war."
His fierce opposition to the Iraq War, launched by President George W. Bush, went far toward creating the schism that now exists between him and the Republican establishment.
"The damage this war has done to our country will play out for years to come," he wrote in his 2008 book, "America: Our Next Chapter."
"While it is easy for nations to blunder into war, they never blunder into peace," he added.
"If I ever get out, if I ever can influence anything, I will do all I can to prevent war," he told Berens.
His opposition to the 2009 surge in Afghanistan put him at odds with the president who is now nominating him. The surge showed a rare moment of support for Obama among many Republicans, with Hagel as a standout exception.
But his willingness to be an independent voice has won him cheers as well.
"He's a guy with really serious foreign policy chops and someone, frankly, who hasn't been afraid to depart from his party when he thought they were wrong," Murphy said in an interview with CNN.
Apology for 'insensitive' remark
As defense secretary, Hagel would oversee a military that recently dropped its "Don't Ask, Don't Tell" policy for gay and lesbian personnel -- a policy he supported. Battles continue over whether same-sex marriages can take place at some U.S. bases.
So his perspective on gays and lesbians carries particular weight.
In 1998, he opposed James Hormel, an openly gay man, for an ambassadorship. Hagel questioned whether Hormel was suitable, describing him as "openly, aggressively gay."
In December, 14 years later, he apologized, calling those comments "insensitive."
"They do not reflect my views. I apologize to Ambassador Hormel and any LGBT (Lesbian, Gay, Bisexual, and Transgender) Americans who may question my commitment to their civil rights."
The Log Cabin Republicans, a group that supports gay rights, argues the apology was "too little, too late."
But gay rights activist Rick Jacob, head of the Courage Campaign, said he supports the president making his choice for defense chief, and noted that "no one trying to derail (Hagel's) nomination attacks his qualifications."
Hagel's support for Israel questioned
Concerns about Hagel's support for Israel could prove to play a big role in confirmation hearings.
In addition to calling for talks with Iran, which openly antagonizes Israel, Hagel has spoken out against some additional sanctions -- a cornerstone of Obama's foreign policy aimed at pressuring Tehran amid questions about the country's nuclear program.
Graham noted that Hagel has wanted Israel to talk with Hamas, a "terrorist group that lobs thousands of rockets into Israel. He also was one of 12 senators who refused to sign a letter to the European Union trying to designate Hezbollah as a terrorist organization."
That and questions about his remark on a "Jewish lobby" have drawn criticism from across the political spectrum and from some Jewish organizations.
"Senator Hagel would not have been my first choice, but I respect the president's prerogative," Abraham Foxman, head of the Anti-Defamation League, said in a statement.
"I trust that the confirmation process will provide an opportunity for Sen. Hagel to address concerns about his positions. ... I particularly hope Senator Hagel will clarify and explain his comments about the "Jewish Lobby" that were hurtful to many in the Jewish community."
Hagel joined two other senators in introducing a resolution in June, 2007, pushing for a two-state solution to the Israeli-Palestinian conflict. The resolution called on Hamas "to recognize the State of Israel's right to exist, to renounce and end all terror and incitement, and to accept past agreements and obligations with the State of Israel."
Rabbi Aryeh Azriel of Temple Israel in Omaha, Nebraska, a longtime friend of Hagel's, told CNN that Hagel is "definitely a friend of Israel. He is independent, has wonderful, fresh ideas to try to reengage the discussion about the Middle East."
Azriel grew up in Israel, and said he personally supports the idea of doors being "opened for negotiation even with Hamas and Hezbollah."
'Thorough vetting' ahead
Sen. Mitch McConnell, the Republican leader in the Democratic-controlled Senate, vowed Hagel would receive a "thorough vetting" just like any other presidential nominee.
"Whoever is nominated for secretary of defense is going to have to have a full understanding of our close relationship with our Israeli allies, the Iranian threat, and the importance of having a robust military," McConnell said on ABC's "This Week." "And if Sen. Hagel is nominated, he'll be subjected to the same kinds of review of his credentials as anyone else."
Hagel has generally avoided public comments since word surfaced that he could be nominated as defense secretary.
But a line from his 2006 biography offers insight into who he is and how he would lead at the Pentagon.
"I'm a hard-edged realist. I understand the world as it is," he said. "But war is a terrible thing. There's no glory, only suffering."
CNN's Mike Mount, Kevin Liptak, Jill Dougherty, and Catherine Shoichet contributed to this report.