The White House is sending Vice President Joe Biden to Ukraine for talks with the acting president and prime minister.
A White House statement says Biden will leave Washington Monday to discuss the international community's efforts to help Ukraine move forward on constitutional reform and for what the Obama administration says will be a free and fair presidential election on May 25.
The talks will also focus on the situation in eastern Ukraine where an Easter Sunday truce barely lasted a few hours before it was shattered by a gunfight at a checkpoint in the pro-Russian city of Slavyansk. Three people were killed. It is not clear exactly what happened.
Russia says it is outraged by what it calls a provocation by Ukrainian nationalists and extremists. Ukraine blames the attack on Russian special forces.
The violence also puts an international deal signed last week in Geneva in jeopardy.
The agreement calls on all armed illegal groups in eastern Ukraine to disarm and leave. The agreement also calls for for a mission by European monitors. But the pro-Russians who have taken over government buildings in about a dozen eastern cities have so far showed no sign of backing down.
The demonstrators are demanding the right to hold referendums on splitting with Ukraine and joining with Russia. A vote last month in Crimea led to the Russian annexation of the Ukrainian peninsula.