Prime Minister Vladimir Putin's United Russia party was leading in Russia's string of regional and municipal elections held on Sunday, electoral commission officials said early on Monday as the opposition cried foul.
United Russia headed the polls in all nine regions where regional parliamentary elections were held, officials cited by the RIA Novosti news agency said.
The ballot count was complete in only four cities, where United Russia candidates were voted in as mayors, officials added.
The party which wins the regional elections may present its candidate for the post of the region's governor, which is appointed by the president.
The full results of the over 3,000 elections held Sunday were to be known on Monday, the central electoral commission said, adding that no serious violations were registered.
However, the opposition Communist party slammed the elections as a "return to shady technologies of the 1990s."
"We noted illegal campaigning, attempts to pressure voters, and the results are determined not by appealing to the voter, but by throwing in ballots through the early voting mechanisms," the Communist party's electoral headquarters chief, Ivan Melnikov, said as quoted by RIA Novosti.
Other opposition parties, Just Russia and LDPR, voiced their intention to join the Communists in registering their protests with the prosecutor general's office as well as local prosecutors.
United Russia, which promised to tackle the economic crisis and uphold social obligations, could face difficulties in the Vladimir region, 200 kilometers (125 miles) east of Moscow, and in the Far North Nenets region, where the ruling party may not obtain an absolute majority, the Russian press wrote.
Putin suggested Friday that the world economic crisis could be longer than first expected and that the times were "difficult" for Russia, while warning his critics not to oppose the current policies he considers efficient.
Russians are increasingly discontent with their government, with 43 percent of a recent poll's respondents disapproving as compared to last year's 35 percent, the independent Levada opinion center said.