Vice President Joseph Biden upped the stakes on Tuesday for passing the Strategic Arms Reduction Treaty in the lame-duck session, just as the White House lost a potential GOP ally in its push.

Biden issued a statement warning that Congress’ failure to ratify the new arms deal with Russia in the coming weeks “would endanger our national security” and result in no verified nuclear reductions.

“The new START Treaty enjoys broad, bipartisan support. The Senate has held 18 hearings on the Treaty. It was approved by the Foreign Relations Committee with bipartisan support. It has been endorsed by prominent former officials from both parties,” he said.

“The time to act is now and we will continue to seek its approval by the Senate before the end of the year,” he said.

The vice president’s tough talk on the issue came hours after Senate Minority Whip Jon Kyl (R-Ariz.) rejected President Barack Obama’s calls for action this year.

The White House has been courting Kyl for support on the issue, but he pointed to a “combination of other work Congress must do and the complex and unresolved issues related to START and modernization” as a reason to punt on the treaty for now.

Biden singled out Kyl when reiterating that Obama has gone above and beyond his predecessors in ensuring the modernization of the nation’s nuclear infrastructure, a priority for the Arizona Republican.

“We have made clear our plans to invest $80 billion on modernization over the next decade, and, based on our consultations with Senator Kyl, we plan to request an additional $4.1 billion for modernization over the next five years,” the vice president said.