U.S. President Barack Obama on Thursday urged the Congress to vote on the new U.S.-Russia arms reduction treaty by the end of this year.

Speaking to reporters after a Cabinet meeting, Obama said he hoped the Senate would ratify the new Strategic Arms Reduction Treaty (START) with Russia, which has gained the approval of the Senate Foreign Relations Committee and is now waiting for a floor vote in the upper house, by the end of this year.

The new START treaty, signed on April 8 in Prague by President Obama and his Russian counterpart, Dmitry Medvedev, replaces the 1991 pact that expired in December last year.

Administration officials and political experts believe the ratification of the new treaty will get more difficult, if not impossible, when the new Congress is sworn in next year.

Republicans failed to take control of the Senate in the mid-term elections but significantly narrowed their seat gap with Democrats.

Republicans are more skeptical of the new treaty, with some of them saying the treaty may restrict U.S. capabilities on developing missile defense systems and that it lacks sufficient verification measures. Some others even say a "yes" vote is only possible if Obama spends more money to upgrade the country's existing nuclear stockpile.

Obama also said he had invited congressional leaders from both parties to the White House on Nov. 18 to discuss what could be done during the lame-duck session. Incoming House speaker John Boehner, and Senate Minority leader Mitch McConnell, current House Speaker Nancy Pelosi and Senate Majority Leader Harry Reid, among others, were on the president's invitation list.

"What's going to be critically important over the coming months is going to be creating a better working relationship between this White House and the congressional leadership that's coming in," the president said.

Obama said the upcoming bipartisan discussion would focus on topics such as the economy, tax cuts and unemployment insurance, among others.

"It's clear that the voters sent a message, which is that they want us to focus on the economy and jobs," he said. "We've got to provide businesses with some certainty about what their tax landscape is going to look like."