Yushchenko signed an order Monday disbanding the parliament and calling for new legislative elections, promising they will be held in line with the Constitution and scheduling them for May 27.
He accused the majority coalition, led by Prime Minister Viktor Yanukovych, of trying to expand its power base through unconstitutional means, notably by welcoming defecting lawmakers. By law, only entire factions can join the ruling coalition.
Despite the presidential decree, the Supreme Rada decided not to cancel its meeting and adopted a number of resolutions Monday night.
In its address to the nation, parliament said the president had no justification to dissolve the body.
During an emergency government meeting last night, Yanukovych said Yushchenko should cancel the order and sit down at the negotiating table.
Ukraine's latest political crisis was triggered by the defection of 11 opposition members of the pro-presidential Our Ukraine and the Tymoshenko Bloc to the majority coalition March 23.
On Monday, Yushchenko held consultations with the Rada speaker and faction leaders, following which he broadcast his dissolution order in a televised address to the Ukrainian nation.
The latest reports said that coalition supporters are converging on the Supreme Rada building in Kiev, where they intend to protect parliamentarians from "orange" forces, Ukraine's Channel 5 reported Tuesday.