Arms treaty debate increasingly testy in Senate

President Barack Obama speaks before signing the Healthy, Hunger-Free Kids Act of 2010 at Harriet Tubman Elementary School in Washington December 13, 2010.

WASHINGTON (Reuters) - Debate in the Senate over President Barack Obama's strategic nuclear arms treaty with Russia grew increasingly testy on Monday but the White House expressed confidence lawmakers would approve the accord before their Christmas break.

Republican senators pushed for passage of a series of amendments in an effort to kill the New START nuclear arms treaty by forcing a renegotiation with Russia. Russian Foreign Minister Sergei Lavrov warned in an interview with Interfax that any amendment would be a deal-breaker.

The treaty, which would cut deployed strategic atomic weapons to 1,550 for each side within seven years, is one of President Barack Obama's top priorities for the current legislative session. The White House said the president was calling senators to line up support.

The agreement, signed by Obama and Russian President Dmitry Medvedev in April, is a centerpiece of the U.S. leader's bid to "re-set" relations with Russia, whose assistance Washington has recently sought on issues ranging from Iran's nuclear program to Afghanistan.

Analysts say Senate rejection of the treaty would be a major blow to warming ties between the two countries, leading the Kremlin to question Obama's ability to deliver on major bilateral issues and giving ammunition to Russian hawks who oppose the thaw in relations with Washington.

The collapse of the pact would also inflict political damage on Medvedev, who has embraced Obama's efforts to improve relations and stepped up Russian support for U.S. efforts to rein in Iran's nuclear program.

The treaty has become bogged down in partisan feuding in the Senate. Republican senators have become increasingly frustrated over the Democrats' press to complete as much legislation as possible before a new Congress with greater Republican representation takes office on January 5.

Democrats moved on Sunday to end debate on the treaty and force a vote by Thursday. It was unclear whether they could muster the two-thirds majority need for approval of the treaty in the 100-member Senate.

POLITICAL CHECKLIST

Senate Republican leader Mitch McConnell charged that the administration was rushing lawmakers to a decision on the arms treaty in order to "tick off another item on someone's political check list before the end of the year."

"The American people don't want us to squeeze our most important work into the final days of a session," McConnell said.

But Senate Foreign Relations Committee Chairman John Kerry rejected that the decision was rushed, noting senators have been working on it for 18 months and had repeatedly delayed debate at the request of Republicans who wanted more time.

McConnell and several other senior Republicans announced on Sunday they would vote against the agreement, but White House spokesman Robert Gibbs said Obama was working the phones trying to sway senators to support the treaty and was confident of approval this week.

"The White House believes that before Congress leaves town the Senate will ratify the new START treaty," Gibbs told reporters at a White House briefing.

There has been far less public or political debate over the treaty in Russia. The Russian State Duma has yet to approve the accord and Medvedev has made clear that parliament should not ratify the treaty until U.S. Senate approval is certain.

Konstantin Kosachyov, the pro-Kremlin chairman of the international affairs committee, said Russian lawmakers would carefully examine the U.S. Senate's resolution of ratification and other declarations before proceeding with their own vote.

(Additional reporting by Steve Gutterman in Moscow and Alister Bull, Thomas Ferraro and Richard Cowan in Washington; Editing by Vicki Allen)