The longshoremens strike that bottled up U.S. ports from Maine to Texas has put Joe Biden in a tough political spot five weeks out from the presidential election.

Tens of thousands of dockworkers walked off the job early Tuesday morning in a contract dispute with the group representing port employers. The work stoppage could deal a serious blow to commerce since the workers handle everything from fruit to auto parts coming into the country via container ship.

A long-lasting strike will pull Biden in opposite directions: The union-friendly president would surely like workers to secure a strong contract with good raises, but hed also want to avoid any economic damage that could drag down Vice President Kamala Harris and other Democrats this fall.

Joe Biden became president in part to put more power in workers hands, not to take power away from them, said Seth Harris, a professor at Northeastern University who previously advised Biden on labor issues. But theres going to be mounting and increasingly intense pressure on him if the strike lasts for weeks, and certainly months, to intervene.

The president could step in and seek a court injunction that would force workers back onto the job for an 80-day cooling off period in which talks would continue. But Biden said just ahead of the strike that he had no intention of invoking the Taft-Hartley Act, the 1947 law that empowers the president to intervene in work stoppages that affect national security.

Its collective bargaining, Biden told reporters Sunday. I dont believe in Taft-Hartley.

Biden weighed in on the side of the dockworkers again on Tuesday, noting that ocean carriers made record profits during the pandemic supply-chain squeeze.

Its only fair that workers, who put themselves at risk during the pandemic to keep ports open, see a meaningful increase in their wages as well, Biden said in a statement.

The union representing East and Gulf Coast dockworkers, the International Longshoremens Association, has called for a $5 per hour raise in each year of the six-year contract, which would bring hourly wages from $39 per hour to $69 by 2030. The union is also demanding protections against automation it says the carriers will use to kill good-paying, middle-class jobs.

The group representing employers, the United States Maritime Alliance, did not comment on the strike but said Monday there had been movement from both sides in negotiations shortly before the walkout.

Presidents have used Taft-Hartley 37 times to intervene in labor disputes over the past eight decades, according to the Congressional Research Service. Biden has never done so, but he did sign a bill passed by Congress to preempt a rail strike and force a deal on those workers in 2022. (Railways fall under a separate collective-bargaining law than the ports and most private-sector businesses.)

Joining the bipartisan push to prevent the rail strike undermined Bidens reputation as the most pro-union president since at least Franklin Delano Roosevelt , as it took away the rail unions leverage in negotiations. Employers that can rely on an injunction would feel less pressure to reach a deal at the bargaining table.

This time, Biden would surely like to avoid injuring his administrations standing with organized labor, especially as most major unions, with the exception of the Teamsters , are rallying behind Harris candidacy.