A majority of almost 12,000 unionized railroad workers voted to reject a tentative labor agreement brokered in part last month by President Biden, the first dismissal by members of a dozen labor groups that must accept the deal or risk a strike.

More than 6,600 members of the Brotherhood of Maintenance of Way Employees voted against the tentative agreement compared to 5,100 votes in favor, the division of the International Brotherhood of Teamsters said in a statement Monday.

The vote results in a “status quo” period in which no strike can take place while the union resumes bargaining with freight railroads, according to the statement. No “self help” may occur until after Nov. 19 at the earliest, it said.

The result signals continued discontent over compensation, working conditions and sick-leave policies among some of the more than 100,000 union-represented workers of U.S. freight railroads. Lengthy, contentious labor talks were at an impasse until a hands-on push by Biden and his administration helped secure a preliminary accord with just hours to spare before a work stoppage that risked halting the flow of some 40% of long-haul U.S. cargo.

Four other unions have approved the pact, while seven more are scheduled to vote through mid-November. If one union were to go on strike, others could refuse to cross the picket line, and rail companies could respond in kind with a nationwide lockout. That’s what triggered the last rail shutdown in 1992, when the International Association of Machinists went on strike against CSX. It took less than an hour for the other freight companies to lock out their workers.