Biden campaigned heavily for Democrats in the 2010 midterm elections, maintaining an attitude of optimism in the face of predictions of large-scale losses for the party. Following big Republican gains in the elections and the departure of White House chief of staff Rahm Emanuel, Biden's past relationships with Republicans in Congress became more important. He led the successful administration effort to gain Senate approval for the New START treaty. In December 2010, Biden's advocacy for a middle ground, followed by his negotiations with Senate minority leader Mitch McConnell, were instrumental in producing the administration's compromise tax package that included a temporary extension of the Bush tax cuts. Biden then took the lead in trying to sell the agreement to a reluctant Democratic caucus in Congress. The package passed as the Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010.