KIEV — Viktor Yanukovych, the front-runner in Ukraine’s runoff vote for president on Feb. 7, declined on Monday to take part in a television debate with his rival, Yulia Tymoshenko, calling her election pledges “dirt and evil.”

Aggressive pro-Tymoshenko advertisements have been flagging a possible TV face-off between the two rivals, scheduled for Monday evening, saying: “The one who wins these debates will be Ukraine’s next president.”

But Yanukovych, who often stumbles over his words and prefers scripted set pieces, declined to accept the challenge from Prime Minister Tymoshenko, a voluble public performer.

Tymoshenko, 49, had earlier called him “a marionette of the mafia,” referring to the powerful oligarchs backing his campaign.

“Notwithstanding these torrents of dirt and evil poured by Tymoshenko, I will not use her methods of struggle,” Yanukovych said in an address to voters. “I believe that concrete deeds and the word that one gives is more important than sweet and pleasing phrases. This is why I deem it indecent to be dragged into empty talk and compete in lies in the run-up to the election.”

Tymoshenko, presented now with the opportunity of making a one-sided political broadcast opposite an empty chair, confirmed on her web site that she herself would be there.

Yanukovych enjoys strong support in his native eastern Ukraine and the south, while Tymoshenko’s power base lies in the nationalist west and in central regions.

Over the weekend, Tymoshenko took her impassioned pro-European campaign into her rival’s heartland, but her call fell mostly on deaf ears in the Russian-speaking port of Odessa.

The fast-talking prime minister rattled off a list of her government’s achievements and repeated her mantra that Ukraine needs cleaner politics when she faced an audience on Saturday in the bustling southern city, rich in Russian imperial history.

The system of cronyism and corruption backed by rich tycoons and their business interests must be replaced, she said, and the country faced a stark choice on Sunday. “The first path is one where Ukraine has very good relations with Europe, one with which we could create European business, traditions and laws,” she told her audience. “And the second path is the path dictated by a few companies in Ukraine.”

The speech would have drawn delirious cries of support in the west and center of Ukraine. But it drew only polite applause in Odessa. In the first round of the election on Jan. 17, 50 percent of voters in Odessa chose Yanukovych and only 10 percent backed Tymoshenko.

Yanukovych won the first round of the election with 35.32 percent of votes, slightly more than 10 percent ahead of Tymoshenko.

In Odessa, Tymoshenko chose to speak in Ukrainian — the state language — although she herself was born in the Russian-speaking east.

“Ah, nothing I have heard here from her is going to change my mind. I’ve heard this all before,” said chemistry student Alexander, after listening to Tymoshenko.