President Vladimir Putin, who continues to envoy wide popularity in Russia, has named First Deputy Prime Minister Medvedev as his successor.
Medvedev, who also chairs the state gas giant Gazprom, is way ahead of his three rivals in the opinion polls.
Critics say Medvedev enjoys unfair media coverage. Others say Medvedev's popularity is also due to an eight-year economic boom under Putin that has left many Russians feeling better off.
Three other candidates are running in the election -- Communist Party leader Gennady Zyuganov, Liberal Democratic Party of Russia head Vladimir Zhirinovsky, and Democratic Party head Andrei Bogdanov.
None of them present a significant challenge to Medvedev. Zyuganov and Zhirinovsky are both polling at less than 10 percent, while Bogdanov is forecast to win less than 1 percent.
On January 27, Russian election officials barred opposition leader Mikhail Kasyanov from running, saying there were too many invalid and suspect entries on his signature lists of supporters.
Kasyanov, who served as prime minister under Putin from 2000 to 2004, called on voters to boycott what he called a "farce" election.
Former world chess champion Garry Kasparov intended to contest the election as a liberal opposition figure. His supporters, however, were not allowed to rent halls for a required nomination gathering. Boris Nemtsov, another opposition figure, announced in December 2007 that he would not run.
Observers say interest is focusing on how much of Putin’s popularity Medvedev can inherit at the ballot box and how much power Putin will retain.
Putin is constitutionally banned from seeking a third consecutive term. He says he could become prime minister if Medvedev takes over the presidency.
The official start of the presidential campaign is overshadowed by a bitter dispute between Moscow and the Organization for Security and Cooperation in Europe's (OSCE) election-monitoring body.
Russia on February 1 accused the OSCE's Office for Democratic Institutions and Human Rights (ODIHR) of trying to sabotage the vote. Foreign Ministry official Sergei Ryabkov said, "There is a continuing, open sabotage in the OSCE of our proposals on adopting a collective, consensus-based agreement on election monitoring, so we are doing what we must do in accordance with the principle of the sovereign equality of states."
ODIHR reacted by saying Russia was "attempting a unilateral reinterpretation" of its commitments.
Earlier in the week, ODIHR warned Russia it would not monitor the presidential vote unless Moscow eases restrictions on its monitors.
ODIHR withdrew from Russia's December parliamentary elections after Moscow invited only a small group of monitors late in the campaign. Putin’s Unified Russia party went on to win a landslide victory.
Russia's Central Election Commission said its chairman, Vladimir Churov, has invited ODIHR Director Christian Strohal for talks in Moscow next week.