WASHINGTON — A year after being lauded for its plan to replace thousands of aging, gas-powered mail trucks with a mostly electric fleet, the U.S. Postal Service is facing congressional attempts to strip billions in federal EV funding. In June, the Senate parliamentarian blocked a Republican proposal in a major tax-and-spending bill to sell off the agency’s new electric vehicles and infrastructure and revoke remaining federal money. But efforts to halt the fleet’s shift to clean ene...