WASHINGTON — Few issues have focused Washington’s contentious energies in recent weeks more than the nomination of former Nebraska senator and maverick Republican Chuck Hagel to the post of defense secretary.

Republican senators have delayed, chastised and publicly humiliated the nominee at every opportunity. Democrats, while quietly toeing the line for the president, have expressed their own reservations and even, discreetly, asked the White House if there wasn’t a better candidate available.

What’s surprising is not the level of opposition to Hagel’s candidacy, but that it surprised anyone when it surfaced. Hagel has been an outspoken critic of many of the signature Republican foreign policy positions of recent years, vociferously opposing Bush’s Iraq policy, openly calling for diplomatic contact with terror groups like Hamas and Hezbollah, and speculating with apparent equanimity that the ayatollahs of Iran would responsibly wield a nuclear weapon.

Considering the gap between many of his positions and those of even Democratic senators, it should also not surprise anyone that the fight over Hagel has not been a clean one. His detractors suffered a blow this week when one of the growing number of circumstantial claims against him — that he once received money from a nonexistent group called “Friends of Hamas” — turned out to be either an honest misunderstanding of a joke, or a dishonest one.

Hagel’s supporters, meanwhile, have been forced to tread carefully around the fairly obvious point that the former senator has spent the past few months disavowing — with suspiciously convenient timing — the very positions that have come to define him politically.

In the end, nearly everyone in Washington concedes that Hagel will be the next secretary of defense. The president has stood by his choice, and the arithmetic, at least in the Senate, is heavily tilted in favor of the president.

Why, then, have Hagel’s opponents clung so stubbornly to their doomed campaign? In the pro-Israel camp, most centrist groups, including the camp’s 900-pound gorilla AIPAC, have pointedly sat out the fight, in no small measure because they didn’t want to be seen to lose it.

What do groups such as the Emergency Committee for Israel, Christians United for Israel or ZOA, not to mention senators Lindsey Graham, Kelly Ayotte, John McCain, Ted Cruz, and others, gain from continuing to challenge the confirmation?

Simply put: while they will no doubt lose the confirmation battle, in an important sense they have already won the policy war.

Since Obama’s reelection victory in November, the parties in Washington have jostled for position in an attempt to determine the political significance of the reelection. Obama has signaled a more aggressive commitment to pursuing progressive domestic policies while Republicans have tried to show they still have some power to hinder their implementation.

By opposing Hagel’s nomination so stridently, his opponents have already forced the former senator to publicly retract and apologize for past statements and views. And by continuing the fight, they have almost guaranteed that Hagel’s tenure as secretary of defense will be hopelessly politicized. Both Republicans who dislike him and Democrats who grudgingly backed him will be watching the new secretary closely for signs of weakness or a return to his unpopular past views.

It’s an especially inauspicious start following the widely celebrated and largely apolitical tenures of the past and current defense secretaries, Bob Gates and Leon Panetta. Hagel will begin his tenure with a level of partisan suspicion and dislike unknown since the end of Donald Rumsfeld’s term in 2006.

As one astute Republican observer told the Times of Israel this week, “the relationship is totally poisoned. I can’t imagine that Chuck Hagel can be a successful secretary of defense. Here’s a guy who over half of the Senate gave a vote of ‘no confidence’ to last week. The feeling was his personal heroism would enable him to go into the Pentagon with the political capital to cut the budget. He may in fact be confirmed, but it’s hard to see how he will be able to work. He’s going to be limping into the Pentagon.”

And a veteran Democratic activist: “Hagel’s already lost. Democrats will be relieved if he’s gone; they don’t like him on Israel, on Iran and because he’s a Republican.”

As several observers have noted, Obama’s very insistence on Hagel as his defense chief suggests that Hagel’s opponents are right to be worried, that the nomination means something. When it comes to foreign and defense policy, Obama’s first term was marked by continuity with the Bush policy. The timetables for withdrawal from Iraq and Afghanistan largely followed those established before Bush left office. They were driven by the professional planning staff rather than any change in thinking in the Oval Office.

Hagel’s nomination matters because it signals to many in Washington, and around the world, that Obama is looking to dramatically reshape US foreign policy.

The fight over Hagel won’t end before the the formal vote on Tuesday — and not even then. The forces opposing him, like those who have come out in his favor, including J Street and a handful of “realist” former ambassadors and foreign policy officials, are engaged in a battle over policy, not personality. Republican senators, together with a few Democratic colleagues who will grudgingly vote for his confirmation, will be watching him closely for any perceived missteps in the years to come.

All in all, not an ideal starting point for a defense secretary, especially one whose chief responsibility will be the unenviable task of drastically reducing the budget and size of the department he has been asked to run.