Viktor Yushchenko was sworn in as president of Ukraine on Sunday, two months after huge protests over his loss in a fraud-plagued election plunged the ex-Soviet republic into political crisis.

Yushchenko (search), a Western-oriented reformer, took the oath in the Verkhovna Rada parliament, placing his hand on a copy of the constitution and an old Bible (search).

Afterward, some deputies repeatedly shouted "Yu-shchen-ko, Yu-shchen-ko," an echo of the chanting that filled Kiev during the showdown with his Kremlin-backed rival.

But others stood stonily unapplauding, a reflection of the deep political tensions that Yushchenko will face as the country's third post-Soviet leader.

Yushchenko was declared the loser of a Nov. 21 election that international observers said was severely marred by vote fraud. Hundreds of thousands of people poured into Kiev's streets to protest the vote, and demonstrations continued for weeks.

The Supreme Court annulled the election and Yushchenko won a Dec. 26 rerun, beating Viktor Yanukovych (search), the prime minister at that time, by 8 percentage points.

But Yanukovych raised a series of legal challenges to the revote, the last of which was rejected by the high court on Thursday, paving the way for the inauguration.

Yanukovych has vowed to take his complaints to the European Court of Human Rights. The court has no enforcement mechanism, but such a move could be an unwelcome shadow on Yushchenko's intentions to push for Ukraine's closer integration with the European Union and NATO.