WASHINGTON -- A White House adviser says he thinks the outgoing Senate will vote on a nuclear treaty with Russia before the end of the year and that there is support to ratify the arms pact.

David Axelrod calls the New arms reduction treaty called START "a critical piece" for U.S. national security.

The accord would place limits on the number of nuclear warheads each country is allowed to possess, and provide for a new inspection and verification program.

Some Republicans are skeptical about the terms of the treaty and say there isn't enough time left on the Senate calendar to give the treaty the attention it requires.

Axelrod says ratification will help the U.S. in terms of cooperation with Russia on issues such as Iran and North Korea.

He tells CBS' "Face the Nation" that "we have to get it done. We can't delay that."