Rights activists charged Wednesday that authorities were pressuring voters to cast ballots for the United Russia party in Sunday's elections, and a communist leader said the campaign was the dirtiest he's ever seen.

President Vladimir Putin, meanwhile, told foreign diplomats that the parliamentary elections would be honest and said Russia is firmly committed to democracy and human rights.

"We know the value of authentic democracy and are interested in conducting honest, maximally transparent and open elections," Putin told dozens of ambassadors at a reception in the Kremlin.

"I am certain that this is precisely what these elections will be," he said.

Putin dismissed allegations that he has rolled back democracy. "We are on the path of democratic development, and the priority here remains the provision and realization of human rights and freedoms," he said.

Kremlin opponents, though, said their campaigns have been subject to harassment, and activists said the pressure on voters means a free and fair election is impossible. Several election monitoring and watchdog groups told reporters Wednesday that government officials are trying to ensure a big turnout and overwhelming victory for United Russia.

Putin has said that a big victory by United Russia will give him the "moral right" to maintain influence in Russia after he steps down as president in May. He announced last month that he would lead the party's ticket, effectively turning the vote into a referendum on his rule.

The expected overwhelming victory for United Russia would give Putin a popular mandate and a loyal parliament to limit the clout of his successor — and possibly lay the groundwork for a return to the presidency in 2012 or sooner.

Government officials across Russia are using their official powers to intimidate opposition campaign workers and candidates, the watchdog groups said.

"If we talk about real political competition, real political discussion — that is completely absent from this campaign," said Liliya Shibanova, head of Golos, a Russian election monitoring organization.

Amnesty International said it has seen "numerous attempts" by authorities to restrict freedom of assembly, association and expression for journalists, rights activists and opposition political groups in recent months. These actions, the group said in a statement, have made it "difficult, if not outright impossible, to express dissenting views."

Alexander Kynev of the Foundation on Information Policy said several candidates had been pressured into dropping out of the race, often with threats that their businesses would suffer or that they would fired from their jobs.

"All of this is taking pathological forms — there is pressure on absolutely everybody," said Kynev, whose group monitors elections.

Opinion polls predict a big victory for United Russia, with one forecasting that it will get more than 80 percent of parliament seats. But the party is waging a lavishly funded campaign as if the results were in doubt; banners and billboards line bridges and streets around Moscow boosting Putin and the party.

Communist Party leader Gennady Zyuganov, who has contested numerous elections since the 1991 Soviet collapse, said the campaign was "the dirtiest and most disgusting" he had seen.

"The main intrigue is whether the (state) falsification mechanism will work to the maximum capacity or whether we will manage to curb it somehow," he told reporters.

Putin opponents — including former world chess champion Garry Kasparov — accuse the pro-Kremlin youth group Nashi of waging a campaign of harassment.

"These Kremlin hoodlums keep staging provocations against me," Kasparov said after an opposition protest Saturday.

Concern about the elections increased last week after the Organization for Security and Cooperation in Europe announced it would not send observers, saying Russia had delayed issuing visas so long that they would be unable to do their jobs. Putin claimed the United States, seeking to undermine trust in Russia, was behind the decision.

Addressing the ambassadors Wednesday, Putin warned against outside interference.

"We've done everything to rid Russia of internal turmoil," he said. "I must repeat that we will not allow these processes to be corrected from outside."

Putin has increasingly accused the West, and particularly the United States, of trying to impose its own concept of democracy on Russia. He has cast Moscow's Cold War foe as a threat to Russia's resurgence and world security.

"We need a decisive break with what divided the world in the past along ideological lines, a rejection of the policy of diktat and the concept of containment," he told the diplomats, in a clear reference to the United States.