Add-on provision could let truckers work more than 80 hours a week.

WASHINGTON ― Want to keep the government open? Want to fund the Zika response? The trucking industry and Republican allies in Congress say the price for that could be weakening rest rules for truck drivers, sources said.

The industry is trying to latch onto the stopgap bill that Congress must pass this month to combat Zika and to fund the government until Dec. 9, hoping to slip in a provision that would permanently block a rest regulation for truck drivers that the Federal Motor Carrier Safety Administration has tried to implement since 2013.

The rule would ensure that drivers take off at least two nights a week and drive no more than 70 hours. It was enacted because research suggested the best, most restorative sleep happens at night, and because accidents jump dramatically when drivers are fatigued.

The industry and many drivers believe this rule robs them of flexibility. Forcing drivers to sleep at night means they have to drive during the daytime, when there are more vehicles on the roads and more accidents, they argue.

Sources familiar with talks over the government funding bill and Zika legislation say Republicans are pushing the unrelated trucking provision, and that Democrats are reluctant to go along.

“They want to make the blockage of the rule permanent,” one of the sources said, speaking on background because matters were still being negotiated.

Although trucking policy has nothing to do with Zika or short-term government appropriations, the industry has repeatedly used funding crises to attach riders that it favors and cannot pass through the regular legislative process.

The trucking lobby, which spends more than $20 million a year to influence Congress, has managed to block the rule before by getting it suspended for more study. It won that concession in the infamous “CRomnibus” spending bill that kept the government from shutting down shortly before Christmas in 2014.

The offices of Senate Majority Leader Mitch McConnell (R-Ky.) and Appropriations Committee Chairman Sen. Thad Cochran (R-Miss.) did not answer questions about the provision. And since the details of the current bill are not public, it was unclear what the new trucking language would be.

It could be similar to provisions that the trucking industry got added to earlier Zika and funding bills that have not passed Congress. One such provision in the Senate would let drivers stay behind the wheel for 73 hours each week, with an additional 8.5 hours permitted for other work.

The idea has not been studied by safety experts and none of the sleep provisions pushed by the industry have been subjected to congressional hearings.