WASHINGTON—Roughly half of all cars and light trucks sold in the U.S. by 2030 would be electric, hydrogen-fuel cell or plug-in hybrid vehicles under voluntary targets to be announced Thursday by the Biden administration and backed by auto makers contingent on government support.

General Motors Co. , Ford Motor Co. , and Chrysler maker Stellantis NV said their commitment hinges on federal funding for manufacturing and supply-chain research and development, purchase incentives and a national electric-vehicle charging network.

Leaders of those companies and the United Auto Workers are set to attend a White House event Thursday afternoon, where administration officials will also announce tougher fuel-efficiency standards.

The new standard would be a fleetwide average of 52 miles per gallon by 2026, according to a senior administration official. The mark was originally set at 54.5 mpg by mid-decade under the Obama administration, but gradually revised downward and ultimately set at 40 mpg by former President Donald Trump.

The shift to electric vehicles will help auto makers reach those higher fuel-efficiency standards. But in a joint statement, the companies said the voluntary targets for electric-vehicle sales “can be achieved only with the timely deployment of the full suite of electrification policies committed to” by the administration in the roughly $1 trillion infrastructure plan now moving through the Senate and related initiatives.