U.S. President-elect Joe Biden's incoming chief of staff on Sunday said the federal government needs to sign off on transition team efforts this week so that Biden's team can receive national security briefings and address COVID-19. "What we really want to see this week ... is the General Services Administration issue that ascertainment," Ron Klain said on NBC News' "Meet the Press." Trump's tweet acknowledging Biden's win - before later saying he did not concede - had no bearing on the actuality of the election, Klain added.