Russians unhappy with the prospect of six more years under President Vladimir Putin are expected to protest nationwide on January 28, backing Aleksei Navalny's call for an election boycott amid warnings from authorities that they will be tough on demonstrators deemed to have broken the law.

Navalny, an anticorruption crusader and opposition leader, called for the boycott after being barred from the March 18 presidential election due to a financial-crimes conviction that he and his supporters contend was Kremlin-engineered retribution. He has dismissed the vote as the "reappointment" of Putin, who has been president or prime minister since 1999.

With the Kremlin controlling the levers of political power nationwide after years of steps to suppress dissent and marginalize political opponents, it is virtually certain that the election will hand Putin a new six-year term. Political commentators say Putin, 65, is eager for a high turnout to strengthen his mandate in what could be his last stint in the Kremlin, as he would be constitutionally barred from seeking a third straight term in 2024.

Navalny has accused the rest of the field of presidential hopefuls of playing into Putin's hands and aiding what he says is a Kremlin bid to portray the vote as a legitimate, competitive contest.

The planned rallies come days after a Moscow court ordered the closure of a foundation crucial to the presidential campaign Navalny has sought to conduct, and as reports of police searches of his campaign offices and harassment of his supporters mount.

On January 26, Russia's Supreme Court revealed that it had declined Navalny's appeal to be allowed to run for president.

On January 25, police issued a stern warning to anti-government protesters. At a meeting with top Moscow police officials, First Deputy Interior Minister Aleksandr Gorovoi said that police will respect the right of citizens to hold public gatherings, as provided by the constitution and other legislation -- but emphasized they would "absolutely toughly...prevent violations of these laws."

In Moscow, Navalny has called on demonstrators to gather on a central street despite city authorities' refusal to grant permission for a rally there, setting the stage for a potential confrontation.

In a blog post on January 27, Navalny urged people to come to the rallies on January 28, writing that "to stay at home is to send them (those in power) the signal: 'I'm ready to endure this for another six years.'"

He also wrote that in 80 percent of cases, authorities have granted permission for rallies at the requested sites for January 28, but not in Moscow or St. Petersburg.

Police have repeatedly cracked down on demonstrations organized by Navalny in the past. More than 1,000 people were detained in Moscow alone on March 26, 2017, when Navalny organized protests in some 100 cities nationwide. Law enforcement authorities also cracked down hard at a protest in May 2012, the day before Putin returned to the Kremlin for his current term after a stint as prime minister.

Navalny appeared this week at a European Court of Human Rights hearing in his case against Russia over repeated incidents in which he has been detained and jailed.

Days before the police warning, a Moscow district court ruled on January 22 that the foundation Navalny and his allies have used to rent premises and pay salaries at campaign headquarters should be shut down. Navalny's campaign chief, Leonid Volkov, described the ruling as absurd and vowed to appeal.

That ruling came days after the Constitutional Court refused to review a complaint from Navalny over the Central Election Commission’s decision in December to bar him from the presidential election.

Navalny supporters have complained of an upsurge in harassment by the state in recent weeks, saying police have searched offices and seized pamphlets calling for an election boycott.