* Protesters take to streets to back new status quo
* Leaders vow to take sole control of their regions
* Russian-speaking east regions traditionally back president (Releads, adds detail on protesters, Tymoshenko)
KHARKIV, Ukraine, Feb 22 (Reuters) - A bid by regional leaders loyal to President Viktor Yanukovich to challenge the legitimacy of the national parliament appeared to founder on Saturday, after thousands of protesters rallied in eastern Ukraine in support of the political changes in Kiev.
The meeting of governors of mainly Russian-speaking regions in the northeastern city of Kharkiv had raised the possibility of a split in the vast former Soviet republic of 46 million. The leaders denied that this was their intention.
In Kiev, the parliament has passed a series of measures that would reduce the president's powers and pave the way to the formation of a national unity government and early presidential elections.
Mikhaylo Dobkin, Governor of Kharkiv region in northeast Ukraine, told regional leaders meeting in the city: "We're not preparing to break up the country. We want to preserve it."
But a resolution adopted at the meeting questioned the legality of the parliament's measures and assumed responsibility for safeguarding regional law and order because central powers were "paralysed".
These sentiments were not echoed by many of Kharkiv's residents however.
Around 3,000 protesters gathered in the city centre on Saturday, proclaiming their support for the new status quo.
The regional leaders' pledge to assert control over the protest movement was put to the test later in the day, when several demonstrators entered Kharkiv's administration offices.
A picture posted on the official Facebook page of supporters of the Kiev "Maidan" protests showed a group of protesters seated casually around a large conference table in the building, one of them sporting a Ukrainian flag as a cape.
In another sign Yanukovich's regional supporters were not calling the shots, the president's arch-nemesis Yulia Tymoshenko walked free from the Kharkiv hospital where she had been held under prison guard for most of the time since she was convicted in 2011 on charges of abuse of office while prime minister.
TALK OF A SPLIT
Many politicians have warned of a looming partition in Ukraine, which broke peacefully from the Soviet Union in 1991, since people took to the streets late last year to protest against Yanukovich for spurning political and trade deals with the European Union. Western Ukraine is broadly pro-EU.
Some Ukrainians are also worried by calls in Crimea for the region to again become Russian territory, nearly six decades after Kremlin leader Nikita Khrushchev, a Ukrainian, redrew internal Soviet boundaries to make a gift of the peninsula to Ukraine.
"The revolution has been won in Kiev, in part of Ukraine, but not in the whole of Ukraine. We still have many risks," said Volodymyr Fesenko, a political analyst at the Kiev-based Penta think-tank.
However imminent pro-Yanukovich upheaval appears unlikely.
Following the leaders meeting in Kharkiv, two of its main participants Governor Dobkin and the city's mayor Gennady Kernes quietly slipped over the border into Russia.
"Mr Dobkin and Kernes have left Ukrainian territory," local media quoted a parliamentary spokesman as saying. (Reporting by Gabriela Baczynska in Moscow, Writing by Timothy Heritage and Alessandra Prentice; Editing by David Gregorio)