Opposition groups and political rivals are launching a new wave of criticism against Russian Prime Minister Vladimir Putin hoping to erode his support before next month's presidential election.

Liberal Democratic party presidential candidate Vladimir Zhirinovsky and Communist party presidential candidate Gennady Zyuganov both lashed out at Mr. Putin Thursday during a debate on state television.

Zhirinovsky criticized Mr. Putin for failing to attend debates but suggested the reason was that the prime minister would have a hard time defending his record over the past 13 years. He said, “everything that happened during all these 13 years has a lot of negatives.”

But some of the harshest criticism Thursday came from former Soviet leader Mikhail Gorbachev. Gorbachev told students at a Moscow University Mr. Putin has “exhausted” his potential as leader and warned political unrest will only get worse if Mr. Putin is elected president.

Mr. Putin served two terms as president, from 2000 to 2008, before becoming prime minister and is seen as the heavy favorite to win Russia's presidential election in March.

But both Mr. Putin and his allies appear to be aware of the growing discontent.

Opposition rallies have been growing in size and in frequency, and Mr. Putin's campaign Thursday announced plans for its own rally on February 23. Officials said up to 200,000 people would take part, marching through the streets of Moscow to the Kremlin. Opposition groups, which have already staged some of the biggest rallies since the fall of the old Soviet Union, had already been planning a rally of their own for February 26.

Mr. Putin also sought to pick up some momentum by offering new ways to take on rampant corruption that has many Russian voters upset.

The prime minister Thursday proposed a new, one-time windfall payment for tycoons who reaped billions from the country's controversial privatization program in the 1990s. He also encouraged businesses to work more closely with the government to draft policy and create legislation.

Many Russians view the process that transferred state-owned assets to the private sector as rigged

But during his speech to students, former Soviet leader Mikhail Gorbachev said it would be difficult for Mr. Putin to change the country's direction, especially because he is surrounded only by his associates and cronies.

The former Soviet leader and Nobel Peace Prize winner, best known for policies like “glasnost” and “perestroika” , said Russia needs “systemic changes, and not just some handouts or sporadic steps.'' He warned that protests will spill into the streets, like with the Arab Spring, if reforms do not come more quickly.

Mr. Gorbachev initially supported Mr. Putin, but has grown increasingly critical of his ability to lead.