Secretary of State John Kerry is in Paris for a critical meeting with Russia's top diplomat.
Secretary Kerry tried to convince the Russians to speak directly with Ukrainian leaders, but couldn't get them in the same room. He is expected to propose a peaceful way out for Russia.
The U.S. will ask Moscow to send its troops back to bases, to accept international monitors, and to endorse May elections to set up a new government in Kiev.
Russia claims its troops are protecting ethnic Russians in Crimea.
The Obama Administration wants to impose economic sanctions on Russia if it does not pullback its troops, but some European allies, especially Germany, are reluctant to go along.
Russian President Vladimir Putin has warned any sanctions would result in what he called serious mutual damage.
While the diplomatic wheels turn, Russian and Ukrainian troops are peacefully co-existing for now in Crimea.
Russian troops have surrounded several bases, but Ukrainian wives are permitted to bring food to their husbands.
One Ukrainian officer told CBS News his troops are crushed emotionally, but they will never surrender.