US President Barack Obama on Saturday renewed his call on US senators to quickly ratify the new START nuclear arms treaty with Russia, warning that failure to approve it would result in serious consequences for the country's security. 'Without ratification this year, the United States will have no inspectors on the ground, and no ability to verify Russian nuclear activities,' Obama said in his weekly radio address. 'Without ratification, we put at risk the coalition that we have built to put pressure on Iran, and the transit route through Russia that we use to equip our troops in Afghanistan,' the president continued. 'And without ratification, we risk undoing decades of American leadership on nuclear security, and decades of bipartisanship on this issue. Our security and our position in the world are at stake.' The treaty -- signed by Russian President Dmitry Medvedev and Obama at an elaborate ceremony in Prague in April -- restricts each nation to a maximum of 1,550 deployed warheads, a cut of about 30 percent from a limit set in 2002. The agreement, a top Obama foreign policy initiative, replaces a previous accord that lapsed in December 2009 and also requires ratification by Russia's lower house, the Duma. Republicans have said they need to be sure that the US nuclear arsenal will be modernized and that the treaty will not hamper US missile defense efforts -- but some acknowledged privately that they did not want to hand Obama a major diplomatic victory before the elections. The task of ratifying the accord will be even tougher in January when a new Congress, elected in November 2 polls in which Republicans routed Democrats, takes office. In a further sign of trouble for the treaty, 10 Republican senators-elect called in a letter for the ratification to be delayed until next year. But Obama made it clear that failure to act fast would be dangerous for the United States. 'The choice is clear: a failure to ratify New START would be a dangerous gamble with America's national security, setting back our understanding of Russia's nuclear weapons, as well as our leadership in the world,' Obama said in the address. 'That is not what the American people sent us to Washington to do.' 