MOSCOW — Aleksei A. Navalny, the most vocal critic of the Kremlin, announced on Tuesday his intention to run for president of Russia, though he is facing a court trial that could make him ineligible to participate in the campaign.

“There have been no true elections in Russia since 1996, and this is one of the reasons of our plight,” Mr. Navalny said in a video statement, posted on his new campaign website. “I will participate in the election, and I will fight for victory.”

Apart from Mr. Navalny, only Grigory A. Yavlinsky, the leader of the liberal party Yabloko, has declared his intention to run for the post. President Vladimir V. Putin has deflected questions about his own candidacy, saying it is too early to talk about it. But he is widely expected to run and, in light of his soaring approval ratings and control over the news media, is expected to win.

The vote is scheduled to take place in March 2018.

A lawyer by training, Mr. Navalny, 40, emerged as Russia’s most prominent opposition politician on the wave of public protests that followed parliamentary elections in 2011, seen by many as flawed.