President Barack Obama took aim Saturday at Republican senators standing in the way of a nuclear arms reduction pact with Russia, saying they were abandoning Ronald Reagan's lesson of nuclear diplomacy: "Trust but verify."

 Sen. Mitch McConnell, R-Ky., didn't mention Obama's push to ratify the new START weapons treaty with Russia, but said extending expiring Bush-era tax cuts needed to be the top priority.

Obama, speaking from a NATO summit in Portugal, used his weekly radio and Internet address to focus on international affairs at a time of increased political gridlock at home as the GOP prepares to take control of the House in the new Congress next year.

Describing his nuclear efforts as part of a five-administration continuum, Obama said the treaty to cut the permitted number of U.S. and Russian long-range nuclear warheads by a third was "fundamental to America's national security."

The president went to great length listing the prominent Republicans from previous administrations who back the deal, including former secretaries of state Colin Powell, George Shultz, Jim Baker and Henry Kissinger. He cited GOP Sen. Dick Lugar's support, but suggested that other Republican senators were playing politics with national security.