Like Nicolae Ceausescu — the brutal and sinister Romanian leader who, even after being taken captive in December 1989, continued to believe that he would prevail — Mr. Yanukovych seemed to persevere in the belief that he could hold on. After misjudging the mood on the street time and time again, he was simply overtaken by reality.

In a television interview given in Kharkiv on Saturday after protesters had taken control of his offices, his palatial residence outside Kiev and other once-impregnable centers of power, Mr. Yanukovych complained indignantly that the events in Kiev had prevented him from attending a Soviet-style congress in Kharkiv of politicians and dignitaries from eastern and southern Ukraine.

“I wanted to take part in today’s congress,” he said, dressed in a dark blue suit as if attending an official engagement, “but it turned out I could not attend. I could not waste time because I had to be in communication all the time” with Kiev.

He went on to declare that he had not resigned and had no intention of doing so, denouncing “traitors” in his own camp and dismissing protesters as hooligans and vandals who had staged a coup. Recalling that he had bounced back from trouble before and rebuilt his political power base, the Party of Regions, after the tumult of Ukraine’s 2004 Orange Revolution, he vowed to stay in the country and make a public report every day on what he was doing to re-establish his position as president.

Mr. Yanukovych has not been heard from since. Even his official presidential website, which was still under his control through the takeover of Kiev by protesters on Saturday, finally died on Sunday. At the same time, his last allies jumped ship, with his party issuing a scathing statement denouncing him as a coward, a criminal and a crook.

The events that led to his ouster accelerated early last week after a month of relative calm. On Tuesday, empowered by a new aid package from Russia announced the day before, Mr. Yanukovych pressed to remove an encampment of antigovernment activists from Independence Square, where they had been cursing his government since November.

Squads of riot police overpowered the outer ring of defenses protesters had set up and advanced to within 25 yards of a stage in the center of the square, called the Maidan.