WEST MIFFLIN, Pa. — It's one the few things Vice President Kamala Harris and former President Donald Trump agree on: opposing the sale of U.S. Steel to the Japanese company Nippon Steel.

But the proposed deal is shattering party loyalty in parts of western Pennsylvania where some steelworkers feel they're being used as political talking points.

"I'm pissed," said Chris Kelly, the mayor of West Mifflin, a small town near Pittsburgh. "I believe everybody's being played as a pawn."

Kelly, a Democrat, said he was initially skeptical of Nippon buying U.S. Steel, which operates plants in West Mifflin and surrounding communities known as the Mon Valley. The company has been making steel here since its inception in 1901. It employs some 4,000 people across Pennsylvania and has said it sustains more than 11,000 indirect jobs and brings in $3.6 billion in economic impact to the region.

During an interview inside his garage — which doubles as his mayoral office — Kelly said Nippon won him over by promising billions of dollars in investments.

"I've learned what the deal is about," he said, adding that it would protect jobs and pensions. "I wish [national politicians] were here today to talk to actual union workers in the mill and the effect it would have on them if they stop this deal in its tracks. It's too important."

Kelly is bucking his own party. Two people familiar with the matter confirmed to NBC News that President Joe Biden is preparing to announce that he will formally block the sale. The news was first reported by The Washington Post.

A White House official said the Committee on Foreign Investment in the United States hasn't sent a recommendation to Biden — the next step in the process.

Biden opposed the sale during a visit to Pittsburgh in April. Earlier this week, during her own visit to the Steel City, Harris said she opposed it, too.

"I couldn't agree more with President Biden," she said. "U.S. Steel should remain American owned and American operated, and I will always have the back of America steelworkers."

Trump is against the deal, too.

But U.S. Steel's CEO, David Burritt, is warning that without Nippon's investment, he'll have to pull resources out of western Pennsylvania, potentially costing the area thousands of jobs.

Troy Stephenson, a union member who has worked at U.S. Steel for 27 years, said, "We worry about our jobs all the time."

"Right now, with what we know, we feel like Nippon is the better deal," he said.

Still, union leadership argues that the deal would benefit stockholders, not workers. In an interview with NBC News, David McCall, the United Steelworkers president, said he didn't believe threats of U.S. Steel pulling out of Pennsylvania.

"I think it is the most baseless, irresponsible threat and statement that any CEO could possibly make," he said. "I take no great satisfaction in being opposed to this deal, other than it does not meet the needs of our members or our retirees, and certainly not the needs of national defense."

McCall said his union's opposition to the detail was largely because it did not meet the criteria of its collective bargaining agreement and his members believed that Nippon might move some of its assets from the region to Arkansas.

Sen. John Fetterman, D-Pa, has come out strongly against the sale.

"I'm calling bull---- on the U.S. Steel executives," he said in a written statement Thursday. "As I've always said, I will follow and stand with the United Steelworkers against the shameless executives looking for a golden parachute."

The sale and the possibility it could be nixed is now deeply dividing this region, pitting members of the same party — and even the same union — against each other in a key battleground state.

Kelly, the West Mifflin mayor, said he was bewildered with both Harris and Trump.

"How could this be the only thing in the whole political race that they agree on?" Kelly said. "Come to where it's affecting the people. Don't make this decision from Washington, D.C."