WASHINGTON (Reuters) - A federal appeals court on Monday brought to an end President Barack Obama’s bid to overturn a ruling that threatens to gut his signature healthcare law by putting the case on hold until after President-elect Donald Trump, who aims to repeal Obamacare, takes office. The Obama administration had appealed a judge’s May ruling favoring the challenge filed by Republicans in the U.S. House of Representatives against a key part of the 2010 law. But the U.S. Court of Appeals for the District of Columbia Circuit agreed to a request by the Republicans to delay its consideration of the government’s appeal until after Trump takes office on Jan. 20. The Obama administration opposed the move. If the law is repealed by Congress, the case would be moot. The court’s decision to put the case on hold will not have an immediate effect on the law, as the lower court ruling was put on hold pending the appeal. The court said both sides should provide an update on the status of the case by Feb. 21. The challenge targeted government reimbursements to insurance companies to compensate them for reductions that the law required them to make to customers’ out-of-pocket medical payments. Trump has said he favors repealing and replacing Obamacare but would consider retaining certain elements.  The law has enabled millions of previously uninsured Americans to obtain health insurance, but Republicans condemn Obamacare as a government overreach and have mounted a series of legal challenges. The Obama administration appealed U.S. District Judge Rosemary Collyer’s ruling that the government cannot spend billions of dollars in federal funds without congressional approval to provide subsidies under the healthcare law to private insurers to help people afford medical coverage. The House Republicans argued that the administration violated the U.S. Constitution because it is the legislative branch, not the executive branch, that authorizes government spending. The Obama administration has interpreted the provision as a type of federal spending that does not need to be explicitly authorized by Congress. The U.S. Supreme Court in 2012 and 2015 issued major rulings authored by conservative Chief Justice John Roberts that preserved Obamacare and rejected conservative challenges. 