By Nandita Bose and David Shepardson WASHINGTON (Reuters) -U.S. President Joe Biden's strategy of backing politically crucial unions while avoiding strikes that cripple the economy has hit a bump in Detroit. During a summer of labor unrest, Biden has touted his pro-labor policies by speaking out for unions, while his administration behind the scenes tries to smooth the way for deals with employers to avoid costly walkouts, union leaders and administration officials said. But in a reminder of how hard it is to appease energized workers while tamping down on price hikes that cause inflation, Bid...
