Russia will face explosive public discontent if Prime Minister Vladimir Putin's United Russia maintains its overwhelming dominance after State Duma elections in December, A Just Russia founder Sergei Mironov said in an interview.

"If a one-party monopoly is preserved, I predict unpleasant events in our country," said Mironov, who was ousted as Federation Council speaker in May.

"I am not saying it will be revolution, but it will be very uneasy in this country. The situation will explode," he said.

Mironov has backed Putin loyally but has a poisonous relationship with his United Russia party that has worsened ahead of the Duma elections and a March presidential vote in which Putin may run.

Waning support among citizens worried about their budgets and tired of the entrenched bureaucracy means United Russia may receive only about 40 percent of the vote in elections, Mironov said.

A convincing victory for United Russia would give Putin firm grounds to seek a return to the presidency after a four-year hiatus and also would ensure his grip on Russia remains tight if he decides not to run.

Political analysts say opinion polls and recent regional election results indicate United Russia may be hard pressed to maintain its controlling two-thirds majority in the Duma without widespread fraud.

Mironov warned that however it is achieved, United Russia's continued dominance would be a greater danger than a more diverse Duma he said would emerge as the result of a free and fair election.

"One must not fool people and press down for so long on this public discontent," he said in the interview late last week. "God forbid we should see another revolution in Russia."

Mironov is far from the first official to warn of the perils of a return to Soviet-style single-party rule. The most prominent political figure to do so is President Dmitry Medvedev, who said in May that the excessive concentration of power could lead to stagnation or even civil war.

Mironov, the same age as Putin at 58, has been a loyal ally and an integral part of Putin's political system. He ran in the 2004 presidential election, but his candidacy was widely dismissed as a ploy to create the impression of competition and he himself indicated that he hoped Putin would be re-elected, which he was. His Just Russia party has supported Putin initiatives.

Mironov said Putin's decision in May to create the All-Russia People's Front was prompted by United Russia's failure to win 50 or even 40 percent in some provinces in regional elections in March, along with results of government-commissioned opinion polls that are not made public.

He said he did not know whether Putin would run for president, but that he clearly has no plans to give up power.

"What Vladimir Putin is doing with the People's Front shows, at the very least, that he does not intend to leave politics."