Days after suffering a setback in the Duma polls and allegations of ballot rigging,Russian Prime Minister Vladmir Putin today went ahead to file his nomination for contesting the March 2012 presidential election,following which he plans to swap places with incumbent Dmity Medvedev. Putin,59,who quit top-Kremlin job in 2008 after serving two terms,in September announced plans to contest for presidency again in March and last month at the United Russia party congress,he was formally nominated party candidate to replace Medvedev. While Putin has been considered a strongman in Russian politics,his United Russia party's performance in the recent parliamentary election was its worst ever. The loss of absolute majority in the sixth State Duma by the ruling party is indicative of drop in the popularity of Putin,but political analyst Sergei Markov believes he will easily win the presidential polls as the anti-incumbency wave was directed against United Russia that was branded by the opposition in the course of the campaign as a 'party of swindlers and thieves'. So far,firebrand leader of ultra-nationalist LDPR Vladimir Zhirinovsky,Communist leader Gennady Zyuganov and A Just Russia party leader Sergei Mironov have expressed their intentions to challenge Putin at the presidential polls. The government,meanwhile,continued to face criticisms over allegations of fraud in the just concluded Duma elections,with Soviet Union's last President Mikhail Gorbachev joining the ranks of the opposition. Gorbachev described the parliamentary polls,in which Putin's party won albeit by a massively reduced margin,as unfair and called for fresh elections,citing "numerous falsifications and rigging."