Yushchenko made the announcement in an address on television today after hours of talks with parliamentary leaders failed to resolve a political standoff in the country.
MORE: Coverage in Ukrainian from RFE/RL's Ukrainian Service.
SLIDE SHOW: Images from the March 31 demonstrations in Kyiv.
"My actions were dictated by the urgent necessity to save the state, its sovereignty, and territorial integrity, and to ensure the constitution of Ukraine, the rights and liberties of people and citizens are upheld,” Yushchenko said during his address. “I would like to underline that this is not only my right -- it is my duty."
"I am calling on the Ukrainian people to make a fair, conscious, and responsible choice which will end this stage of political conflict and will open a new perspective for Ukraine," he added.
The president accused the parliamentary majority led by Prime Minister Viktor Yanukovych of seeking to expand its power base in violation of the constitution, and of making decisions that violated the law.
(with material from agency reports)
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."