WASHINGTON—The Prime Minister’s Office isn’t saying anything about a key U.S. senator’s decision to put President Joe Biden’s controversial electric-vehicle incentives on ice. West Virginia Sen. Joe Manchin, a key Democratic vote in the evenly divided Senate, confirmed today that he’s a “No” on the $1.75-trillion Build Back Better bill. The legislation includes tax credits worth up to $12,500 on U.S.-assembled electric vehicles that are built with union labour—a devastating blow to the Canadian auto industry. The plan has been atop the agenda of countless federal ministers and officials, including Prime Minister Justin Trudeau himself, during multiple in-person and virtual meetings in recent weeks. If officials in Trudeau’s office are breathing a little easier, however, they are refusing to say—likely in part because the reprieve could prove only temporary. After months of meetings with colleagues and officials from Capitol Hill to the White House, including Biden himself, Manchin declared his …