KIEV, March 12 ??“ Ukraine??™s political crisis is set to escalate sharply as two opposition groups, backed by President Viktor Yushchenko, prepare Tuesday to issue an ultimatum to the pro-Russian government coalition over foreign and domestic policies.

Our Ukraine and the group led by former Prime Minister Yulia Tymoshenko on Monday signed the 16-clause ultimatum that demands the coalition to stop challenging Yushchenko on foreign and security policies.

Unless the demands are met, the opposition groups that number more than 200 lawmakers threatened to leave parliamentary sessions to go campaigning throughout the country for new election.

???We may leave the sessions and go propagating our positions in the regions,??? Viacheslav Kyrylenko, the leader of Our Ukraine in Parliament, said.

The ultimatum was signed by the two groups following the meeting between Yushchenko and the lawmakers from both groups at the presidential office. It was the first such meeting over the past year underscoring the significance of the ultimatum.

Yushchenko, who strongly backs the pro-Western alliance between Our Ukraine and the Tymoshenko group, is increasingly challenged by the pro-Russian government of Prime Minister Viktor Yanukovych.

The government, bowing to pressure from Russia, Ukraine??™s only supplier of natural gas, works hard to slow down Ukraine??™s accession to NATO, a bloc that Moscow views as the military threat.

The standoff between the president and the government may escalate into sharp constitutional crisis as both may claim essentially the same powers, such as the right to define the country??™s foreign and defense policies.

The coalition forced Boris Tarasiuk, an architect of the pro-Western policy, to resign as the foreign minister earlier this year. Yushchenko??™s nomination of Volodymyr Ohryzko, a pro-Western diplomat, to the post was also rejected.

The standoff between the president and the government is caused by controversial amendments to the constitution that have come into force last year by shifting some presidential powers, such as the right to appoint and to dismiss ministers, to the prime minister.

But Yanukovych, using the lack of clarity in the amendments over some issues, pushed aggressively for assuming the powers of defining foreign and defense policies thus seeking to marginalize the post of the president.

???It is so sad to see that the government is wasting its efforts on what can be described as usurpation of power,??? Yushchenko said at the meeting. ???These encroachments affect any issue, from the national security to formulation of the law on the Cabinet of Ministers. It seems there is no constructive position besides the encroachments.???

The ultimatum, which is supposed to be declared in Parliament on Tuesday, calls on the coalition to work with the president to change the constitution in order to end the constitutional deadlock.

It also calls on the government to fire Internal Affairs Minister Vasyl Tsushko and Prosecutor General Oleksandr Medvedko, to approve Yushchenko??™s nominees to the posts of the foreign minister and security service, to stop integration with Russia within the so-called Common Economic Space agreement, to remove controversial gas trader, RosUkrEnergo, as key gas supplier and other issues. (tl/ez)