President Obama is reportedly ignoring Republican filibuster threats and nominating former Sen. Chuck Hagel (R-Neb.) on Monday to be his third Defense Secretary, replacing the outgoing Leon Panetta. On Sunday, Senate Minority Leader Mitch McConnell (R-Ky.) said the Senate will give Hagel a "fair hearing like any other nominee." Other Republicans are being somewhat less charitable. "Quite frankly, Chuck Hagel is out of the mainstream of thinking on most issues regarding foreign policy," said Sen. Lindsey Graham (R-S.C.) on CNN. He "has long severed his ties with the Republican Party," and "this is an in-your-face nomination by the president to all of us who are supportive of Israel." Sen. Ted Cruz (R-Texas) similarly said it was "very difficult to imagine a circumstance in which I could support (Hagel's) confirmation," given his "very, very troubling" record regarding Israel. Democrats aren't exactly thrilled about the Hagel nod, either. He is, after all, a Republican. Here's a look at why Obama is going to fight for Hagel, why he needs to fight, and whether the Nebraskan will pass muster among his former Senate peers.

Who is Hagel, and what are his qualifications?
Hagel served two terms in the Senate, from 1997 to 2009, emerging with a reputation for political independence. Before his Senate career, Hagel worked briefly as a newscaster, a businessman, head of the USO military service members' organization, and an infantry squad leader in the Vietnam War, earning two Purple Hearts in 1968. If confirmed, Hagel would be the first defense secretary who served as an enlisted man. Since retiring from the Senate, Hagel has served on Obama's President's Foreign Intelligence Advisory Board.

Why is Hagel a controversial pick?
The Hagel resisters "have four main concerns," says Fred Kaplan at Slate. "They fear that Hagel will cut the military budget," since he said in 2011 that the "bloated" Pentagon budget needs to be "pared down." Second, "they fear that he'll roll over if Iran builds a nuclear weapon." Given his opposition to the Iraq War and subsequent troop "surge," GOP critics also "fear that he's too reluctant to use military force generally." And the most prominent objection: "They fear he doesn't much like Israel; the extremists on this point claim he's anti-Semitic." This is based largely on interviews he gave in 2007 in which he mentioned that the "Jewish lobby intimidated lawmakers," and another one where he noted he was a senator from Nebraska, not Israel. Some gay-rights advocates (and Republicans) also oppose Hagel over a 1998 comment he made in opposing a gay ambassador nominee for being too "openly aggressively gay."

What do his defenders say?
They actually agree with some of the critiques — especially that Hagel is blunt, would favor cutting the Pentagon budget, and will oppose attacking or invading Iran — but see those as reasons to support him, while pointing out that the defense secretary doesn't make the final call on matters of war or peace. And as for the anti-Israel/anti-Semitism charge, says Slate's Kaplan, Hagel's comments "may have been impolitic remarks, but they weren't false — either in strict substance or in spirit." Lots of people in government complain about the Israel lobby, just quietly. The best proof that the attacks against Hagel "are craven or wrong" is that most of the foreign policy establishment, including five former ambassadors to Israel, "reacted in support of Hagel, and in revulsion against these attacks," says James Fallows at The Atlantic. As for the "aggressively gay" comment, Hagel has apologized, and "I think that a lot of people have had their views evolve on LGBT issues over the last 20 years," including Obama, says White House spokesman Tommy Vietor

Why does Obama want Hagel at the Pentagon?
It's simple, says Marc Ambinder at The Week: Obama has been "picking Hagel's brain on subjects as diverse as Afghanistan, China, special operations force posture, and intelligence for several years now," and "of all the possible candidates, he trusts Hagel." So does Vice President Joe Biden, who is friends with his former Republican colleague. That trust will be extremely important, says Ray McGovern in The Baltimore Sun, when Hagel shoots down the "hare-brained schemes" generals and Pentagon insiders will continue to lob at Obama. As "the first secretary of defense in 30 years with lessons learned from direct combat experience," Hagel knows the costs of war, and he's tough and honest enough to put his foot down. If Hagel gets Obama and the Democrats to give up being so timid on military policy, says Peter Beinart at The Daily Beast, Obama can finally put his mark on how Washington views and interacts with the world. Tapping Hagel "may prove the most consequential foreign policy appointment of his presidency."

What are the chances Hagel will be confirmed?
"The White House thinks he will win confirmation," says Reid Epstein at Politico. Most senators easily win Senate confirmation, and "despite the vocal objections of a few GOP senators, only three have explicitly said they will vote against Hagel." Lots of "neoconservative policy activists" and political reporters are calling Hagel's confirmation iffy, says Josh Marshall at Talking Points Memo. "These folks should stop smoking crack." Democrats won't oppose their popular president, and is it plausible that "Republicans uniformly oppose a former member of their own caucus when the issues at stake are complaints that look comical when held up to the light of day?" Not likely. "I look forward to Republican crocodile tears on gay rights — seemingly in large part over something Hagel said in the 90s in support of the Senate Republican caucus's efforts to pillory an openly gay nominee" — as much as the next pundit, but "get ready for a Hagel Pentagon."

Sources: Atlantic, Baltimore Sun, CNN (2), Daily Beast, The Hill, Politico, Slate, Talking Points Memo, The Week