© Jabin Botsford/The Washington Post Sen. Mike Lee (R-Utah) walks to a Senate Republican Policy Luncheon on Capitol Hill on Tuesday. The U.S. government on Wednesday moved one step closer to a potential shutdown, as some Republicans seized on a fast-approaching fiscal deadline to mount fresh opposition to President Biden’s coronavirus vaccine and testing mandates. The emerging conservative campaign quickly divided GOP lawmakers, enraged congressional Democrats and threatened to unravel days of delicate bipartisan talks on Capitol Hill. They appeared receptive to allowing debate to proceed, provided they can have a vote on an amendment to terminate funding for Biden’s vaccination and testing mandates. The top Senate GOP appropriator, Sen. Richard C. Shelby of Alabama, still expressed some confidence that lawmakers could agree in time.