Sen. Marco Rubio (R-FL) announced on Tuesday that he won’t support legislation to prevent an economically calamitous rail strike if it isn’t supported by the union workers.

The Florida lawmaker’s statement, marking an unusual pro-labor position for a Republican, comes as workers at several rail unions have voted to reject an agreement reached between labor leaders and the railroads. A strike, which would be terrible for the economy, could begin as soon as next week unless Congress uses its special power to intervene and impose a labor agreement.