Yushchenko has threatened to dissolve the legislature if the talks fail, leading to early elections.
In his opening speech, he said some political forces are seeking to usurp power in Ukraine.
SLIDE SHOW: Images from the rival rallies
MORE: Coverage in Ukrainian from RFE/RL's Ukrainian Service.
ANALYSIS: Retribution Behind Calls For Early Elections"Essentially, there is a constitutional imbalance emerging in the country," he said. "The balance between different branches of power is being lost. And a creeping, distinct usurpation of power in single hands is under way. Finally, the democratic ideals and values of society are being put into question."
Yushchenko has accused pro-Moscow groups in parliament of encouraging lawmakers from blocs that support him to switch sides. He says this activity goes against the constitution and must be halted.
Several thousand people today gathered in central Kyiv to protest Yushchenko's threat to dissolve th Verkhovna Rada, which is controlled by a pro-Russian coalition.
On March 31, Kyiv saw rival rallies between supporters of the president and backers of pro-Russian Prime Minister Viktor Yanukovych.
(with material from agency reports)
SUBSCRIBE For weekly news and analysis on Belarus, Ukraine, and Moldova by e-mail, subscribe to "RFE/RL Belarus, Ukraine, And Moldova Report."
In his opening speech, he said some political forces are seeking to usurp power in Ukraine.
SLIDE SHOW: Images from the rival rallies
MORE: Coverage in Ukrainian from RFE/RL's Ukrainian Service.
ANALYSIS: Retribution Behind Calls For Early Elections
Yushchenko has accused pro-Moscow groups in parliament of encouraging lawmakers from blocs that support him to switch sides. He says this activity goes against the constitution and must be halted.
Several thousand people today gathered in central Kyiv to protest Yushchenko's threat to dissolve th Verkhovna Rada, which is controlled by a pro-Russian coalition.
On March 31, Kyiv saw rival rallies between supporters of the president and backers of pro-Russian Prime Minister Viktor Yanukovych.
(with material from agency reports)
RFE/RL Belarus, Ukraine, And Moldova Report
RFE/RL Belarus, Ukraine, And Moldova Report
SUBSCRIBE For weekly news and analysis on Belarus, Ukraine, and Moldova by e-mail, subscribe to "RFE/RL Belarus, Ukraine, And Moldova Report."