US Vice President Dick Cheney arrived in Ukraine on Thursday as a bitter row between pro-Western political forces in the ex-Soviet republic threatened to bring down the government.
  
Cheney was expected on Friday to meet President Viktor Yushchenko and Prime Minister Yulia Tymoshenko, whose political feuding has intensified over ties with Russia during its confrontation with Georgia and the West.
  
Cheney has said his visit is intended to bolster US allies in the former Soviet region. Ukraine has applied to join NATO and the European Union, angering Moscow which sees the country as part of its sphere of influence.
  
European officials have suggested Ukraine could be the next flashpoint for tensions between Russia and the West after a war in Georgia last month that has left Russian troops occupying positions deep inside Georgian territory.
  
Yushchenko on Wednesday accused his opponents in parliament of a coup attempt and threatened early parliamentary elections after the prime minister's party sided with pro-Russian deputies to pass laws cutting his powers.
  
Tymoshenko, once a close ally of Yushchenko, in turn accused the president of having "destroyed" the governing coalition by pulling out of an alliance with her party after the approval of the legislation.
  
But Tymoshenko has also called for members of parliament from the president's Our Ukraine party to return to the coalition. The deputies have 10 days in which they can revoke their decision to pull out.
  
On Thursday, the independent daily Gazeta 24, quoting unnamed lawmakers in Tymoshenko's parliamentary bloc, said the prime minister and the leader of the pro-Moscow Regions Party had already agreed to form a new coalition.
  
The report said Tymoshenko would remain as prime minister while the Regions Party leader, the Moscow-backed former prime minister and bitter presidential rival Viktor Yanukovych, would take over as speaker of parliament.
  
"Tymoshenko will dance to Moscow's tune," the Kommersant newspaper quoted a member of parliament from the president's party as warning, reinforcing accusations that Tymoshenko is toeing the Kremlin line.
  
Tymoshenko has denied this but has not spoken out on the Georgia crisis.
  
Ukrainian analysts said the political crisis could set back Ukraine's attempts to join NATO and the EU but that Cheney would seek to keep in place the country's increasingly fragile pro-Western leadership.
  
"Cheney will try to push Ukraine towards preserving the pro-Western coalition," which has not yet been formally disbanded, said Valery Chaly, an analyst at the Razumkov Centre for political and economic research.
  
Segodnya, a newspaper close to the pro-Russian opposition, said the crisis was "very annoying news" for Washington, which wants "Tymoshenko and Yushchenko working together to bring Ukraine into NATO."
  
In other developments, a pro-Russian member of parliament put forward a motion calling for Foreign Minister Vladimir Ogryzkov to be sacked for allowing a US warship to visit the Sevastopol naval base, located in southern Ukraine.
  
Tymoshenko and Yushchenko were the icons of the 2004 pro-Western Orange Revolution and have each been considered Western-leaning politicians despite persistent and sharp disagreements on domestic political issues.
  
Last month however Yushchenko's backers accused Tymoshenko of "high treason" for allegedly siding with Moscow in its conflict with Georgia.
  
Tymoshenko had abstained from a vote to impose restrictions on the movements of Russia's Black Sea fleet, which is based along with the Ukrainian navy in Sevastopol and was involved in military action against Georgia.
  
Cheney is to meet the two leaders separately -- the prime minister for one-on-one talks in the morning, followed by lunch with the president.
  
He is scheduled to visit the Holdomor memorial to Ukraine's famine victims before departing later in the afternoon for Italy.