U.S. President Barack Obama and his Russian counterpart Dmitry Medvedev have held what the White House calls "encouraging" talks on a treaty to succeed the 1991 Strategic Arms Reduction Treaty, or START.
An aide for Medvedev said "the text has been agreed on, by and large."
The two leaders spoke by phone as negotiators from the two countries meet in Geneva to finalize an agreement under which the two sides would each reduce deployed strategic nuclear warheads by about one quarter.
Negotiations to renew and strengthen the old START treaty have been going on for about a year.
Among the sticking points have been Russian opposition to U.S. plans to locate a missile defense system in eastern Europe and questions of monitoring and verification.
Obama is holding an international nuclear security summit in Washington in April, giving the two sides an incentive to have a deal ready to sign by that time.
compiled from agency reports