Vehicle certification is among the functions halted by the nearly four-week partial shutdown of the federal government, meaning automakers could face delays in launching new and updated models if the impasse in Washington drags on, Automotive News reports.

Under the Clean Air Act, new vehicles and engines can’t be sold legally in the U.S. without approval from the EPA. Jim Farley, Ford Motor Co.’s president of global markets, noted last week that the automaker has a number of important products headed to dealerships this year, including the redesigned Explorer and Escape, as well as the new Lincoln Aviator.