WASHINGTON — The US Senate on Thursday overwhelmingly approved Ash Carter to become the country's 25th defense secretary.

After a weeks-long delay while he recovered from back surgery, Carter's nomination sailed through the upper chamber with a final tally of 93-5. He testified for around five hours on Feb. 4 before the Senate Armed Services Committee (SASC) submitted additional answers to the panel on Monday, and it voted unanimously Tuesday to send his nomination to the floor.

A spokesman said Carter's first official day on the job will be Feb. 17.

Carter's confirmation process was a stark contrast to that of his predecessor, Chuck Hagel, who was left politically bruised after a series of attacks by his former Senate Republican colleagues.

This time, there was virtually no opposition to Carter. In fact, since President Barack Obama announced his nomination in early December, Republicans and Democrats effusively praised Carter as thoroughly qualified to run the Pentagon.

SASC Chairman Sen. John McCain, R-Ariz., on Thursday went to the Senate floor to urge his colleagues to support the nomination.

"I have known Dr. Carter for many years during his lengthy service in Washington," McCain said. "He is one of America's most experienced defense professionals, respected by Republicans and Democrats alike.

"I have had the opportunity to work together with Dr. Carter on several issues of shared concern, especially trying to reform the defense acquisition system, improving financial management of the department, and rolling back sequestration," McCain said. "America needs a strong secretary of defense now more than ever."

Sen. James Inhofe, R-Okla., a former Armed Services Committee ranking member, called Carter "a guy who really has the background and the knowledge" for the Cabinet post.

Carter inherits a military recovering from more than a decade of continuouslyat war, and often in multiple theaters. The Defense Department also continues to warn about the ongoing effects of sequestration budget cuts.

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Analysts say Carter's good reputation among Republicans and Democrats in both chambers should help the Pentagon in its messaging efforts trying to get lawmakers to provide relief — or terminate the remaining defense spending reductions.

"Carter's biggest challenges are those outside of his control," said Mackenzie Eaglen of the American Enterprise Institute, adding that the challenges those are one part political and one part bureaucratic.

Eaglen, a former Senate defense aide, listed "the budget battle, the 2016 presidential race and a lame duck Obama" as challenges awaiting Carter.

"Secondly, a White House well known for its tight control over foreign and defense policy that is not going to change six years into the president's tenure," she said, adding "the need to show tangible and measurable results quickly on Pentagon reform" will be another challenge.

But Carter enters office with something Hagel never possessed, Eaglen said.

"The good news for Carter is that Congress is predisposed to work with him, offer an extended honeymoon his predecessor did not enjoy, and give him the benefit of the doubt when problems do arise since he is a known commodity," she said. "Other good news is that Dr. Carter is landing in on a seasoned, well-established team with good rapport, expertise and insights into how to make the most of these remaining 22 months in charge."

The Yale-educated physicist soon will take over for Chuck Hagel.

Some lawmakers, led by McCain, doubt the incoming secretary will have much sway over the Obama administration's national security policies. McCain, citing complaints from two former Obama defense secretaries, says senior White House officials micromanage defense policy decisions.

"I'm confident that he has no influence whatsoever," McCain told reporters last week during a break in Carter's confirmation hearing.

Senate Majority Leader Mitch McConnell, R-Ky., said Thursday he would support Carter's nomination — with a caveat.

"But my support is conditioned on this request: the incoming secretary needs to have the courage to speak truth to power," McConnell said on the floor. "To Congress, yes. But also to his commander in chief."

During his confirmation hearing, Carter vowed to be "a stickler for the chain of command."

"I have promised President Obama that if I am confirmed, I will furnish him my most candid strategic advice," Carter said. "I will also ensure that the president receives candid professional military advice. This is not only consonant with the law as written in this very committee, but with good sense, since our military leaders possess wide and deep experience and expertise."

McConnell also said he wanted to "place one demand on him."

"It would be to leave his successor with our armed forces in a better position to deal with global threats than they are today," McConnell said.

McCain says Carter's main function will be to "manage the Pentagon," saying he's well-suited to do so after holding the building's No. 2 and No. 3 civilian leadership posts.

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