President Barack Obama declared Thursday that he is confident the Senate has the votes to pass the Strategic Arms Reduction Treaty in the lame-duck session, despite a snub from a pivotal GOP Senator earlier this week.

“I’m confident that we should be able to get the votes,” Obama said during a high-profile White House meeting on the treaty in what was his toughest push yet on the issue. Meeting attendees included Secretary of State Hillary Rodham Clinton; former Secretaries of State Madeleine Albright, James Baker and Henry Kissinger; and Senate Foreign Relations Committee Chairman John Kerry (D-Mass.) and ranking member Dick Lugar (R-Ind.).

“For the most part, these treaties have been debated on the merits; the majority of them have passed overwhelmingly with bipartisan support. There’s no reason that we shouldn’t be able to get that done this time as well,” he said, adding that he considers passage of the treaty this year “a national security imperative.”

The White House has been scrambling to build GOP support for ratifying the new arms deal with Russia in the coming weeks; Obama made three references to former President Ronald Reagan’s support for it during his remarks. But he was dealt a blow Tuesday when Senate Minority Whip Jon Kyl unexpectedly pulled his support to act on the treaty during the lame-duck session, citing a crowded agenda. Senate Majority Leader Harry Reid (D-Nev.) later countered that there is time to do it in the coming weeks.

White House Press Secretary Robert Gibbs dodged questions Thursday about whether he thought Kyl’s opposition was political, saying the Arizona Republican’s stated needs relating to the modernization of the nation’s nuclear program “can and will be met easily.” But he suggested politics may be driving Kyl’s stance when asked if the administration is risking putting the country’s prestige on the line if a premature Senate vote on the treaty fails.

“If you were asking that of someone who opposed, I think you’d want an answer to why they would oppose this treaty when all their concerns are being addressed and wonder why they were doing that,” Gibbs said to a group of reporters.

He emphasized that administration officials “have talked to and are going to continue to talk to” Kyl and other Senators about supporting the treaty. He noted that Kerry has personally been talking to Kyl about endorsing START action this year.