A possible new takeover bid for U.S. Steel emerged on Monday, teeing up more turmoil over the once-dominant company’s future after President Biden’s decision to block its acquisition by a Japanese company.

Lourenco Goncalves, the chief executive of an American competitor, Cleveland-Cliffs, said his company had “an All-American solution to save the United States Steel Corporation,” stressing that acquiring U.S. Steel was a matter of “when,” not “if.” But he offered no details of the bidding plans.

The renewed expression of interest from Cleveland-Cliffs comes less than two weeks after Mr. Biden blocked a $14 billion takeover of U.S. Steel by Nippon Steel, arguing that the sale posed a threat to national security. Cleveland-Cliffs tried to buy U.S. Steel in 2023, an offer that was rejected in favor of Nippon’s higher bid.

CNBC reported on Monday morning that Cleveland-Cliffs would seek to take over U.S. Steel and sell off its subsidiary, Big River Steel, to Nucor, another American producer. But Mr. Goncalves, at a news conference later in the day, would not confirm any partnership with Nucor on a bid.

U.S. Steel and Nucor did not immediately respond to requests for comment.

Investors seemed pleased by the potential bid, sending shares of U.S. Steel up as much as 10 percent on Monday when CNBC reported the potential offer. Shares of U.S. Steel finished about 6 percent higher on Monday but are down 23 percent over the past year, including Monday’s spike.

But the fate of Nippon’s proposed takeover remains in limbo. U.S. Steel and Nippon sued the United States government last week in the hopes of reviving their merger, accusing Mr. Biden and other senior administration officials of corrupting the review process for political gain and blocking the deal under false pretenses.

The companies filed a separate lawsuit against Cleveland-Cliffs, Mr. Goncalves and David McCall, international president of the United Steelworkers union. They argue that Cleveland-Cliffs and the head of the union illegally colluded to undermine the Nippon deal, assertions that both defendants called “baseless.”

On Saturday, the companies said the Biden administration had delayed enforcement of its executive order blocking Nippon’s takeover until June, to give the courts time to review the lawsuit.

“The problem is, we can’t make anything happen until the current management and the current board of U.S. Steel make the decision to abandon the merger agreement with Nippon Steel,” Mr. Goncalves said at a news conference in Butler, Pa., on Monday.

Given this rancor, it is unclear how receptive U.S. Steel would be to a new bid by Cleveland-Cliffs. If U.S. Steel does not engage, one option would be for Cleveland-Cliffs to take an offer to shareholders.

U.S. Steel was once the world’s largest steel producer, but the company has fallen in global rankings in recent years. Concerns about its long-term future are rooted in a failure to quickly adopt alternatives to traditional mills that are more energy-efficient and cost-effective. Nippon, U.S. Steel has argued, is the only buyer that can make substantial investments in multiple steel mills and protect jobs.

The United Steelworkers, which represents 11,000 U.S. Steel employees, has voiced strong opposition to the proposed merger with Nippon. The powerful union has said the Japanese company engaged in illegal trade practices and dealt with the union in bad faith. Previously, the union expressed its preference for a merger with Cleveland-Cliffs, which is unionized.

A new bid by Cleveland-Cliffs, if it materializes, risks antitrust scrutiny from federal antitrust regulators, though regulators in the Trump administration are widely expected to take a less aggressive approach to merger enforcement than their Biden administration predecessors.

Matthew Giachelli got the call he anticipated on Thursday morning: The N.F.L. was moving the Rams’ playoff game to Arizona because of the wildfires raging in Los Angeles, and the league needed 200 gallons of paint pronto.

The game on Monday between the Rams and the Minnesota Vikings would now be held at State Farm Stadium outside Phoenix, and it had to look and feel as if it were being played in the Rams’ usual home, SoFi Stadium. That included painting the field with the team’s and league’s logos and colors. The hometown Cardinals, though, did not have some of the needed hues on hand, including the Rams’ blue and yellow.

Giachelli’s company, World Class Athletic Surfaces in tiny Leland, Miss., provides paint to most N.F.L. and top college teams. Within hours, he and his co-workers had loaded five-gallon buckets of nine custom paint colors, as well as stencils for the N.F.L. playoff logos, onto a truck that left Thursday afternoon on a 1,500-mile journey to Arizona.

“I definitely regret what’s going on in California, but I’m glad we could meet their needs,” said Giachelli, the vice president of production and distribution.

Getting the right paint was just one of hundreds of details that the league, the Rams, the Vikings, the host Arizona Cardinals and ASM Global, which operates State Farm Stadium, have juggled since the N.F.L. decided to move the wild-card round game.

The N.F.L. has canceled preseason games and postponed and moved regular-season games over the years because of hurricanes, snowstorms and other calamities. But it had not moved a winner-take-all playoff showdown since 1936, when the site of its championship game was changed from Boston to New York to drum up ticket sales.

A battalion of people — from the front-office workers to the training staffs to the thousands of game-day workers — have been mobilized on short notice. Each game, particularly in the playoffs, generates tens of millions of dollars for television networks, advertisers and stadium operators, and with the season coming down to its last few weeks, there was little margin for error.

“If it can be played, they play it, and in this case, it can be played in Glendale,” said Joe Buck, who will call the game for ESPN on Monday. “We’re in the playoffs now, and you’ve got all this pressure to get this first round finished before Kansas City and Detroit,” which had first-round byes, “get back in.”

A big reason the N.F.L. is the world’s most valuable league is scarcity. There are just 272 regular-season games and 13 playoff games, so each one is of critical importance to the 32 teams. (By contrast, there are about 400 Major League Baseball games every month during the season.) They are also critical to the owners of those teams and the league, as well as broadcast networks, sponsors and other companies that spend billions of dollars a year to attach their businesses and brands to the N.F.L.

It has not escaped notice that one of those businesses, State Farm, will have its name attached to Monday night’s broadcast less than a year after it announced that it would not renew 30,000 homeowner policies and 42,000 policies for commercial apartments in California. (The N.F.L. has donated $5 million to Los Angeles relief efforts.)

With so much riding on each contest, the N.F.L. does everything it can to play every game every year. When the league creates its season schedule each spring, it prepares contingency plans including an alternate site for each game. In 2022, when a massive snowstorm hit western New York, the Buffalo Bills played a home game at Ford Field in Detroit.

During the pandemic, outbreaks in locker rooms forced the league to postpone several games, though none were canceled. When pandemic conditions in Santa Clara County, Calif., deteriorated, the San Francisco 49ers moved to Arizona for a month, playing three home games in State Farm Stadium. Arizona was also a backstop in 2003 when the Chargers moved their home game against the Miami Dolphins because of fires in San Diego.

This time, the fires spread so quickly, the league decided to move the game five days before kickoff. Kevin Demoff, the president of the Rams, said the team had been in constant contact with officials in Los Angeles, who initially thought the game could be held at SoFi Stadium in Inglewood, which was unaffected by the fires.

But that changed midweek, when fires broke out close to the team’s training facility in Woodland Hills, forcing some players and staff to evacuate their homes and for one practice to be cut short. Demoff said he did not want the players and staff to be distracted, nor did he want city and county resources to be diverted for the game when they could be used to help others in need.

Moving the game is “just a recognition that there’s some things bigger than football and we owe this to our community to make sure that this game can be played safely and not be a distraction,” Demoff said Friday.

ESPN was on hold as well. Four of its production trucks were en route to Los Angeles from Pittsburgh when the league told the network on Wednesday night that the game could be moved to Glendale. The crews spent the night in Kingman, Ariz. On Thursday, the plan was to set up in both stadiums in case the league waited until Saturday to decide where to play. So the trucks continued on to Los Angeles while another set of trucks left for Glendale. When the N.F.L. said Thursday that the game had been moved, the first set of trucks, which had reached Ontario, Calif., turned around and arrived in Glendale with time to spare.

The Cardinals also helped out the Rams in ways beyond just lending their stadium. The team’s owner, Michael Bidwill, sent two team planes to Los Angeles to help the Rams get their entourage and equipment to Arizona.