KIEV, Ukraine – President Putin injected himself directly into the election crisis in this former Soviet republic yesterday, strongly attacking the opposition’s central demand for a new presidential runoff.

Tens of thousands of opposition supporters waving Ukrainian flags and wearing orange armbands, sweaters, and scarves rallied for the 11th straight day in Independence Square. While awaiting a Supreme Court ruling on whether to throw out the results of the disputed election, they listened to rock bands and watched large-screen TVs broadcasting the court sessions.

The demonstrators erected a Christmas tree – also bright orange, which is the emblematic color of their movement – in the tent camp they have maintained since shortly after the November 21 runoff. Protesters kept up their blockade of the Cabinet building, banging on drums improvised from metal canisters, the sound echoing off the walls of the imposing Stalin-era building.

Mr. Putin, hosting the president of Ukraine, Leonid Kuchma, again issued a warning to the West. “Neither Russia, nor the European Union, nor international organizations will solve the problems,” he said outside Moscow. “They all can play the role of mediators, but the Ukrainian people have the last word.”

Following Mr. Putin’s remarks, President Bush issued a warning that appeared to be directed at Russia. If there is to be a new election, it “ought to be free from any foreign influence,” Mr. Bush said in comments that were considered more forceful than those he has made in the past.

Mr. Putin had openly supported Prime Minister Yanukovych in the election. The Kremlin fears that a victory by opposition leader Viktor Yushchenko, who favors closer ties with the West, could drag this country of 48 million out of Moscow’s orbit and generate pressure for greater democracy in Russia.

The Supreme Court is considering an appeal by Mr. Yushchenko’s campaign to invalidate the result of the runoff, which the Central Election Commission said Mr. Yanukovych won by about 900,000 votes. The appeal centers on claims of widespread violations across the prime minister’s strongholds in the east and south, near Russia.

The 18 red-robed justices began hearing final arguments but adjourned hours after dark without a decision.

If the court sides with Mr. Yushchenko, it would put him in a strong negotiating position with Mr. Kuchma to schedule a repeat runoff. If the court rules against Mr. Yushchenko’s appeal, Mr. Kuchma’s administration might seek to inaugurate Mr. Yanukovych or schedule new elections with a more attractive candidate.

As the court edged toward a ruling, Mr. Kuchma flew to Russia and won Mr. Putin’s support for his proposal to hold an entirely new election – not just a repeat of the runoff.

“A revote could be conducted a third, a fourth, a 25th time, until one side gets the results it needs,” a grim-faced Putin said in televised comments from the meeting in a sparsely decorated, parquet-floored room at the government’s Vnukovo-2 airport outside Moscow before leaving for India. He said another runoff would likely “yield nothing.”