Incumbent governors in Irkutsk and Nizhny Novgorod struggled to hold onto their posts Sunday as their regions cast ballots in gubernatorial elections.

Incumbent Irkutsk Governor and pro-Kremlin Unity's favorite Boris Govorin was in a tight race with Valentin Mezhevich, a member of the Federation Council, going into the vote. Five other candidates were also in the running.

The election was declared valid by Sunday afternoon Moscow time with more than 25 percent of the region's voters participating, Interfax reported. A candidate must secure more than 50 percent of the vote to avoid a runoff. Preliminary results were expected Monday.

The Irkutsk campaign has been tense. Four candidates filed a suit Thursday charging Govorin of giving the election commission incorrect information about his wife's possessions and of using his office to influence voters. They turned over to the court 20 videocassettes on which Govorin allegedly violated campaign rules in televised remarks, Regions.ru reported. The case was thrown out Saturday.

Meanwhile in Nizhny Novgorod, incumbent Governor Ivan Sklyarov was facing off against State Duma Deputy Gennady Khodyrev, who won a 3 percentage point lead in the first round.

Rustam Bikmetov of the Nizhny Novgorod Research Fund said the incumbent governor had a chance.

"Two weeks ago Khodyrev succeeded because of poor voter attendance, letting the disciplined, older pro-Communist electorate dominate," he said. "This time, there are more younger voters who may change the balance in Sklyarov's favor."