Kremlin critic Alexei Navalny's sudden illness has deprived the opposition party in Russia of its undisputed star and figurehead, and upended his strategy to challenge Vladimir Putin's grip on power at upcoming regional elections.
Potentially exposing a leadership vacuum within Russia's opposition.
44-year-old Navalny remains in a Berlin hospital after a suspected poisoning where his condition remains serious, according to his spokeswoman on Thursday (August 27).
Before he fell ill, he'd been urging supporters to vote tactically for candidates running against the ruling United Russia party in mid-September.
Russians will elect governors, local parliaments and city councillors in what's seen as a dry run for next year's parliamentary elections.
Under Navalny's smart voting plan, supporters receive emails on the eve of regional or local elections - telling them to vote for a specific candidate running against United Russia.
Last year it worked. The strategy spooked United Russia - and it lost a third of its seats in Moscow city elections, though it largely failed outside Moscow.
So what happens now?
Navalny has spent years growing a following though extensive YouTube videos detailing corruption allegations and his energetic personality has brought him fame and credibility particularly amongst young Russians.
His team says it will push ahead with the strategy, with close allies Leonid Volkov and Lyubov Sobol appearing the most likely to continue Navalny's work while he's incapacitated.
Though some analysts say they lack the charisma and political clout to lead the campaign.
That might be in part because leading Russia's opposition is a daunting task.
Navalny has been detained many times and targeted by pro-Kremlin activists.
A Kremlin-linked source said a new leader would soon emerge, saying 'a sacred place never stays empty for long'.