WASHINGTON, Dec 1 (Reuters) - The White House said on Wednesday the U.S. Department of Justice "will vigorously defend" the government"s authority to promote its vaccine requirement in federal contracting after courts blocked the Biden administration from enforcing two vaccine mandates. A U.S. District Judge in Louisiana on Tuesday temporarily blocked the Centers for Medicare & Medicaid Services (CMS) from enforcing its vaccine mandate for healthcare workers.A U.S. District Judge in Kentucky blocked the administration from enforcing a regulation that new government contracts must include clauses requiring that contractors" employees get vaccinated. The legal setbacks, spurred by Republican state attorneys general, conservative groups and trade organizations that have sued to stop the regulations, added to a string of court losses for the Biden administration over its COVID-19 policies. They also come amid concerns that the Omicron coronavirus variant could trigger a new wave of infections and curtail travel and economic activity around the world. The administration"s most sweeping regulation - a workplace vaccine-or-testing mandate for businesses with at least 100 employees - was temporarily blocked by a federal appeals court in early November. "We know vaccine requirements work...We are confident in the government"s authority to promote economy and efficiency in federal contracting through its vaccine requirement and the Department of Justice will vigorously defend it in court," a White House spokesperson told Reuters on Wednesday. On Wednesday, the Biden administration said a total of 92% of U.S. federal workers have received at least one dose of a COVID-19 vaccine. President Joe Biden unveiled regulations in September to increase the U.S. adult vaccination rate beyond the current 71% as a way of fighting the pandemic, which has killed more than 750,000 Americans and has weighed on the economy. Earlier this week, the White House told federal agencies they could delay punishing thousands of federal workers who failed to comply with a Nov. 22 COVID-19 vaccination deadline.