The battle over the next secretary of defense isn’t ultimately about Chuck Hagel. It’s about President Obama and his second-term agenda for the military.

Washington loves a good fight. Nomination battles are a kind of bloodsport here. And Hagel presents a prime target of opportunity.

Disliked by most Republicans, disowned by many Democrats, he has no natural base of support for the Pentagon job. He has, instead, a constituency of one, and that is POTUS.

Does anyone seriously think the former Nebraska senator will be dictating policy on, say, Israel or Iran, any more than Leon Panetta did? In nominating Hagel on Monday, despite plenty of attacks during the trial-balloon phase, Obama was sending the message that he wants his own man to stir things up at Defense, even if that man is a Republican. Otherwise he’d name a technocrat and avoid the messy Senate battle. The president put his own prerogatives front and center.

This is, in short, a proxy war.

If the Republicans can torpedo the nomination, they will make Obama look weak. If Hagel is confirmed but roughed up in the process, the administration will be forced to spend valuable capital.

Nor is such an effort unprecedented. More than two decades ago, a Democratic Senate rejected one of its former members, John Tower, for the Pentagon, largely on the basis of his past drinking and other aspects of his private life. The idea was to weaken the new president, George H.W. Bush, and it worked, while also producing Dick Cheney as a substitute.

Obama wants to complete the U.S. withdrawal from Afghanistan and cut back on Pentagon spending, given the immense budget pressures he faces. Hagel gives him some political cover on those fronts because he can’t be tagged as a left-wing, soft-on-defense Dem.

You would think a Vietnam War veteran with two Purple Hearts would appeal to the pro-military GOP. But you would be wrong.

The president certainly hit those notes in introducing Hagel on Monday, calling him “an American patriot” who “bears scars and shrapnel from battles he fought in our name”—and who understands that “sending Americans to fight and bleed in the dirt and mud” is not something to be done lightly.

Part of this battle is inescapably cultural. Most Senate Republicans don’t much like Hagel because he bucked the party leadership, turned against the Iraq War and, once out of office, campaigned for Democrat Bob Kerrey in his home state. Indeed, Sen. Lindsey Graham called his selection an “in your face” nomination.

Hagel, for his part, broke his silence, telling his home-state Lincoln Journal Star that “the distortions of my record have been astounding” and there is “not one shred of evidence that I’m anti-Israel.”

The case against Hagel rests in part on two major gaffes. A half-dozen years ago, he stupidly referred to the intimidating prowess of the “Jewish lobby,” as if everyone who cares about Israel’s security has to be Jewish. But Hagel also has voted for billions in aid to Israel, and Obama wants to push Bibi Netanyahu to rein in his ambitious expansion of West Bank settlements. It is the Obama policy, not some Hagel doctrine, that has attracted the opposition of pro-Israel groups, though AIPAC won’t officially fight the nomination.

Fourteen years ago, Hagel criticized a Bill Clinton nominee as ambassador to Luxembourg as being “openly, aggressively gay.” (As opposed to passively gay?) That was offensive, and Hagel has apologized.

Hagel has also drawn flak for not taking a harder line against Iran, whose nuclear ambitions loom as a major foreign policy challenge for Obama. But who really believes that military action against Iran is a viable option? Iran has bedeviled every president since Jimmy Carter, and Hagel’s views, while important, are not going to be driving administration policy.

White House press secretary Jay Carney hit the twin subjects hard on Monday, telling reporters that “Senator Hagel has been a staunch supporter of Israel, of Israeli-American relations,” as well as of “a broad sanctions regime that the president has put in place against Iran.”

In case anyone missed the point, Carney said the job of Obama’s team is to “do the work of implementing the president’s policies.”

Finally, Hagel has said the Pentagon budget is “bloated.” In a world in which members of Congress push weapons systems the Pentagon doesn’t want because they generate jobs back home, can there be any serious debate over this assessment? No matter who is SecDef, the defense budget is going to shrink with the U.S. having extricated itself from two wars.

By nominating Hagel, Obama is taking a stand for these priorities. He could have ducked the personnel fight, as he did by giving up on Susan Rice for State. But he can’t evade the bruising battle ahead over defense policy.