The Senate on Thursday rejected an effort to repeal an Environmental Protection Agency rule on power-plant emissions that cross state lines, dealing a blow to lawmakers who support the coal industry.

Fifty-six lawmakers voted against the measure, including six Republicans, mostly from Eastern states, who defected to vote with the Democratic majority. Two Democrats, Sens. Joe Manchin (D., W.Va.) and Ben Nelson (D., Neb.), joined 41 Republicans who voted to institute a less restrictive rule that previously was in place.

The result was a setback for critics who say the new rule’s timeline is too stringent and that it would lead to job losses in the coal industry by causing the closure of coal-fired power plants. It bolstered the position of Senate Democrats who have vowed to fight Republican efforts to stop EPA rules.