One of Vladimir Putin's top critics just hit a major milestone in his quest to become Russia's next president — he's been nominated to run for the office.
Alexei Navalny got enough nominations to officially begin his presidential bid, but he still has some obstacles to overcome.
For one, the government has warned Navalny won't be allowed on the ballot due to a fraud conviction and suspended prison sentence.
Navalny says the conviction was politically motivated.
If he is allowed on the ballot, he'll be facing tough odds against a very popular President Putin.
Putin got almost 64 percent of the vote in the country's last election. The runner-up got just 17 percent.
Even some of Navalny's supporters think his chances of winning are pretty slim. And Navalny himself told CBS earlier this year that he thinks there's a 50-50 chance he'll be killed if he continues his anti-corruption campaign.
