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A Republican Senate aide said the current administration started negotiations on a “bridging mechanism” too late. “Why didn’t they do that weeks ago?” he asked, speaking on the condition of anonymity because of the sensitivity of the topic.

Mr. Kimball said the White House did not have enough time. He blamed the Bush administration for not having started negotiations with Russia during its term, which he said would have given the Obama administration a head start.

Republicans, in turn, said that would not have been prudent because of the two administrations’ different approaches to arms control, with the Obama administration seeking deeper cuts in nuclear arms.

During a visit to Moscow by President Obama in July, both countries agreed to draft a new arms control treaty that would replace START. They also set a goal of cutting the number of strategic nuclear warheads to between 1,500 and 1,675 within seven years. Currently, the U.S. deploys about 2,200 such warheads and Russia is estimated to have between 2,500 and 2,600.