White House: Senate Has to Pass START Before Christmas Recess

President Obama speaks to members of the media in advance of the Nuclear Security Summit in Washington, Sunday, April 11, 2010. AP

Two more Senate Republicans have put their support behind the United States' nuclear arms treaty with Russia, giving momentum to the deal which President Obama says the Senate must ratify before leaving for Christmas vacation.

Maine's two moderate Republican senators Olympia Snowe and Susan Collins both confirmed today that they will vote in support of the Strategic Arms Reduction Treaty (START) agreement.

Collins said in a statement today she will vote to ratify the treaty after receiving reassurances from Secretary of State Hillary Clinton and Defense Secretary Robert Gates regarding the Obama administration's approach to "tactical" nuclear warheads, which are particularly vulnerable to theft or acquisition by terrorists. After Collins wrote to Clinton and Gates regarding her concerns that too much emphasis had been placed on the physical location of Russia's nuclear warheads, the administration officials told the senator that they were also focused on the reduction and security of tactical warheads.

"As the Ranking Member of the Senate Homeland Security and Governmental Affairs Committee, I support the President's commitment to reduce not only the number of strategic nuclear weapons through the New START treaty, but also to reduce, in the future, those weapons that are most vulnerable to theft and misuse - and those are tactical nuclear weapons," Collins said in a statement.

Snowe released her own statement of confidence in the treaty. She pointed out that the Senate has held 18 hearings on the matter since the treaty was signed by the United States and Russia in April.

"I am confident that New START will provide predictability in our relationship with Russia and thus enhance global stability, and most importantly, our national security," she said. "Therefore, if the Majority moves to consider New START under a framework that allows for sufficient debate and amendments, I intend to support the Resolution of Advice and Consent."

White House Spokesperson Robert Gibbs told reporters today that Congress "will not leave" for its Christmas recess until the START treaty is ratified, nor will Mr. Obama leave for his Hawaii vacation until Congress has wrapped up its work for the year. Gibbs said the White House expects a "strong bipartisan vote" on the treaty.

So far Sen. Richard Lugar of Indiana is the only other Republican to say unequivocally he will support the treaty, but some others have signaled they could support it. Sixty-seven senators need to vote in favor of the treaty for it to be ratified.

Stephanie Condon is a political reporter for CBSNews.com. You can read more of her posts here. Follow Hotsheet on Facebook and Twitter.