Ukrainian President Viktor Yushchenko will deliver a nationally-televised address Wednesday evening, hours ahead of a constitutional deadline for naming a new prime minister.

Mr. Yushchenko must either formally nominate political rival Viktor Yanukovych as prime minister by midnight (5 p.m. EDT, 2100 UTC), or alternately he can dissolve parliament.

Ahead of the broadcast, parliament was meeting in emergency session, as the president met with leading lawmakers in a last-ditch push to end the political crisis.

President Yushchenko's allies have signaled they could accept Yanukovych as prime minister, if he agrees not to reverse Ukraine's moves toward membership in NATO and the European Union.

For its part, Yanukovych's Party of Regions returned him to the brink of power largely on the strength of his pledges to align the country more closely with Russia and oppose Ukrainian efforts to join NATO.

Reports from Kiev describe a city gripped with political tension, after the two sides failed to reach a deal in marathon talks that ended early today.

Thousands of his supporters and opponents converged on Kiev Wednesday, and a vigil was under way near the parliament building by mid-day.

Some information for this report was provided by AP.