Manchin flips against Biden’s nominee for labor secretary because of her ‘progressive background’

President Biden’s nominee to become the next Labor Department secretary, Julie Su, was thrust further into jeopardy on Thursday after Sen. Joe Manchin III came out in opposition.

The conservative West Virginia Democrat said he has “genuine concern” that Ms. Su, who is serving as acting secretary and whose nomination has been in limbo since February, is too progressive.

“I believe the person leading the U.S. Department of Labor should have the experience to collaboratively lead both labor and industry to forge compromises acceptable to both parties,” Mr. Manchin said in a statement. “While her credentials and qualifications are impressive, I have genuine concerns that Julie Su’s more progressive background prevents her from doing this and for that reason, I cannot support her nomination to serve as Secretary of Labor.”

Mr. Manchin’s opposition marks a reversal from his prior vote to confirm Ms. Su as deputy labor secretary two years ago. However, he has increasingly voted against Mr. Biden’s nominees as the 2024 election draws near, even as he remains undecided on reelection.

The White House’s headache doesn’t stop with Mr. Manchin.

A White House official said that Sen. Kyrsten Sinema, Arizona independent, who like Mr. Manchin is facing a tough reelection next year, is also leaning against Ms. Su. Ms. Sinema caucuses with Democrats and has not taken a public stance.

Given Senate Democrats’ razor-thin one-seat majority, the White House can only afford one more Democrat defector before being forced to throw in the towel on Ms. Su. All GOP senators are expected to oppose her confirmation.

“The president’s support for Acting Secretary Su is unwavering, and we hope Sen. Manchin and Sen. Sinema reconsider their position,” the White House official said. “President Biden and his team continue fighting for Acting Secretary of Labor Julie Su’s confirmation — because she is highly qualified, experienced and has proven herself time and time again when it comes to delivering for America’s workers and our economy.”

Sen. Mark Kelly, Arizona Democrat, revealed this week he would support Ms. Su. But Montana Sen. Jon Tester, another Democrat facing tough reelection odds, declined to publicly take a position.

Ms. Su took over as acting secretary in March when Labor Secretary Marty Walsh left his post to run the NHL Players’ Association.

It’s not clear when — if ever — Senate Majority Leader Charles E. Schumer will be able to hold a final confirmation vote.

“I think she’ll be a very good labor secretary, and we’re working hard to get her approved,” the New York Democrat told reporters earlier this week.