U.S. President Barack Obama speaks at the White House Tribal Nations Conference at the Department of the Interior in Washington December 16, 2010. REUTERS/Kevin Lamarque

WASHINGTON (Reuters) - Fresh from a shared victory on an $858 billion tax-cut package, President Barack Obama pushed on Saturday for congressional approval of the new START nuclear arms treaty with Russia.

Obama invoked the late Republican President Ronald Reagan as he used his weekly radio address to urge bipartisan support for the treaty. Obama said it was crucial to put a new treaty into place so inspections of Russia’s nuclear facilities could resume after a lapse that began when the old START treaty expired a year ago.

“Without a new one, we won’t be able to verify Russia’s nuclear arsenal, which would undercut President Reagan’s call to trust, but verify, when it comes to nuclear weapons,” Obama said. Failure to approve the treaty would jeopardize Washington’s warmer ties with Moscow, he added.

The START treaty would commit Russia and the United States to cut deployed strategic nuclear weapons to 1,550 for each side within seven years.

Republican senators charged on Friday the treaty would unwisely limit development of U.S. offensive and defensive missile systems. They questioned the benefit of continuing to cut atomic weapons and challenged Obama’s goal of ultimately eliminating all nuclear arms.

Although nine Republicans voted with Democrats to allow debate on the treaty, it was unclear whether all of them would vote to support the accord, which needs a two-thirds’ majority, or 67 votes, to pass in the 100-member Senate.

Late on Thursday, Congress approved the deal Obama and Republicans hammered out to renew expiring tax cuts and extend unemployment benefits in a package aimed at giving the lackluster U.S. economy a short-term boost. The bill, seen as a victory for the president and the Republicans, passed despite objections from many of Obama’s fellow Democrats.

Obama is delaying his departure for a holiday vacation in Hawaii to try to secure passage of START and other legislation, including repeal of the “Don’t Ask, Don’t Tell” policy banning gays from serving openly in the military.

He plans to work the phones next week to try to win support for START, according to White House spokesman Robert Gibbs.