Moscow votes in pivotal election pitting opposition leader against Kremlin-backed incumbent

Moscow is holding its first mayoral election in a decade. Although an incumbent backed by President Vladimir Putin is expected to win handily, the candidacy of charismatic opposition leader Alexei Navalny is changing Russian politics in ways that could pose a risk for the Kremlin in the months and years ahead.

If Navalny can get more than 20 percent of the vote in Sunday's election or even come close to forcing incumbent Sergei Sobyanin into a run-off, it could embolden the opposition in its efforts to one day drive Putin from power.

A vote seen as unfair could trigger protests, just as reports of widespread fraud in a national parliamentary election in 2011 set off the unprecedented protests against Putin's rule.