WASHINGTON — Former Pentagon official Ashton Carter is likely to be President Obama’s nominee for defense secretary, according to administration officials, putting him in line to take over a sprawling department that has had an uneasy relationship with the White House.

Obama spokesman Josh Earnest stopped short of confirming the president’s decision, yet praised Carter effusively for serving “very, very ably” at the Pentagon previously and noted he had been easily confirmed by the Senate once before.

“This is an indication that he fulfills some of the criteria that we’ve discussed in the past,” Earnest said. “He is somebody who definitely deserves and has demonstrated strong bipartisan support for his previous service in government.”

Administration officials said Obama could announce his nominee as early as this week. The officials insisted on anonymity because they were not authorized to discuss the president’s decision-making process publicly.

A physicist with deep Pentagon experience, Carter moved to the top of the White House’s short list after several leading contenders pulled their names from consideration for what is typically a highly sought-after Cabinet spot. If Obama moves forward with Carter’s nomination and he is approved by the Senate, the 60-year-old would replace Chuck Hagel, who resigned as Pentagon chief last week under pressure from Obama.

Hagel’s resignation highlighted ongoing tensions between the White House and the Pentagon, where top officials have complained about West Wing micromanagement and a lack of clarity in Obama’s policy-making. Perhaps as a result of those concerns, Obama found himself with a far shorter list of possible replacements than the White House may have expected.