Alexei Navalny's star is rising. He has more than 1 million followers on YouTube. More than 130,000 Russians have volunteered for his presidential campaign. Despite being officially barred from the ballot, he has established dozens of campaign offices throughout the vast expanse of the world's largest country in an attempt to unseat current President Vladimir Putin.

Navalny, 41, has undergone quite an evolution. When I first met him several years ago, he was a little-known activist investor with an exclusive focus on minority shareholders' rights and fighting corruption in Russia's largest state-controlled companies.

Then in 2013, as a complete newcomer to politics, he ran for mayor in Moscow mayoral elections, going up against a close Putin ally. Navalny lost, but shocked Russia's political establishment by coming in second with more than 27 percent of the vote.

In his pursuit of the presidency, Navalny is now becoming more confrontational and uncompromising. We observed that in the demonstrations he organized on June 12. The government had granted him a permit to hold a demonstration, one of more than 90 planned across Russia. The demonstration would almost certainly have been peaceful.

On the eve of the protest, however, Navalny cancelled the demonstration at the location that had been approved by Moscow officials. Navalny said the city was harassing companies he had approached to build the stage and provide sound and video equipment.

In a late-night YouTube address to his supporters, Navalny told his followers it would be humiliating to hold the demonstration under those conditions. He called on his supporters to gather on Moscow's main thoroughfare instead.

Lacking a permit for the demonstration, the inevitable ensued. Navalny was arrested -- and later sent to a detention facility for 25 days -- before the protests even began. An hour into the protest, police moved in and arrested more than 700 demonstrators. A total of more than 1,000 protesters were arrested at protests across the country.

While the Moscow march began peacefully and the protesters remained peaceful, the end was surreal.

As riot police surged forward, the crowd of mostly young protesters fled to evade arrest. Participants at a nearby re-enactment of various periods of Russian history were caught in the middle.

The Russian actors in period costume scrambled to protect their historical installations. Many Russians who had come to enjoy a day off work watched in horror and disbelief as groups of men and women dressed in traditional Russian garb fended off anyone who might accidentally trample on their trailing clothes.

It felt like a collision of two worlds, and represented an oddity of modern Russian politics. Those who supported Alexey Navalny were pitted against the power of the state, the conflict playing out in the streets of largely apolitical Moscow.

Navalny enjoys the support of many young people. They are often called "Putin's children," because Putin is the only leader they've ever known. Many of Putin's children were at the protest. They told us they want change.

Russians as a whole -- not just young people -- want to change the country's culture of corruption, which runs deep in all aspects of life. The vast majority of Russians are increasingly concerned about graft. The early days of Putin's reign -- when the amount of money Russians had in their pockets grew by 10 percent every year -- are long gone. Plummeting oil prices and, to a lesser extent, sanctions imposed by the West have snuffed out the dynamic economic growth Russians became accustomed to over Putin's first decade in power.

The Kremlin has taken steps to crack down on corruption. The first government minister to be prosecuted for corruption goes on trial this week, and countless governors have been dismissed or jailed. But Russians don't think the government's efforts have gone far enough, and many like what Navalny has to say about getting rid of state-sanctioned corruption.

They like what Navalny stands against. Yet many wonder, what does he stand for?

Dmitry Trenin, the head of the Carnegie Moscow Center, has watched Navalny's anti-corruption campaign grow.

"There's a problem that he has, I think. And the problem is forging his own positive message -- telling his supporters and others, what is it that he favors? Not [what] he is against," Trenin told me.

Navalny dismisses the criticism, saying his opponents are trying to paint him as having no message beyond his anti-Putin crusade. His response is not without merit -- Navalny says he wants to bolster democracy, reduce military spending and increase spending on health care and education. His argument is "Russia First" -- the government should focus on raising the standard of living at home before embarking on interventions abroad in Crimea, Syria and elsewhere.

Russia after Putin

Navalny has emerged as the leader of Russia's fractious opposition movement. Many other opposition activists are in self-imposed exile, languishing in jail or lack the stomach for the struggle Navalny has taken on. Others have ended up dead.

Navalny's current goal is to get on the presidential ballot in December when the official campaign season kicks off. At the moment, that looks unlikely. Officials say his criminal convictions for embezzlement and fraud bar him from taking part in the election. Navalny says those convictions are politically motivated and that ultimately Putin himself will decide if Navalny is allowed to participate. If he is, Navalny's chances of defeating Putin remain miniscule. With official approval ratings above 80%, Putin has the kind of popularity many world leaders can only aspire to.

Trenin, of the Carnegie Moscow Center, calls Navalny a "raw meat politician" who stands no chance against Putin next year, but could still have a chance to eventually take the reins.

"Vladimir Putin will not be forever Russia's leader. At some point there will be an opening," Trenin said. "Whether Navalny will be around when that opening happens, whether things will work for him in the meantime, no one can tell."

Though he hasn't declared his intentions yet, Putin is widely expected to seek a fourth term as president in the March 2018 election. If he wins, Putin will be 71 by the end of the six-year term in 2024, the same age President Trump is today. Putin will have led Russia for nearly a quarter century by then.

Under the Russian constitution, Putin would be barred from running for a third consecutive term as president in 2024. So who's next?

At the moment -- admittedly, these are early days -- Putin has no obvious successor inside or outside the political establishment to lead this country of more than 146 million people.

We traveled to London to meet with Mikhail Khodorkovsky, who was once the richest man in Russia and Putin's biggest nemesis before he was forced into exile. He supports Navalny politically and financially and wants to see him run for president, but he has concerns.

"I have long ago lost my faith in an ability of a single leader to turn over the situation in the country," Khodorkovsky said. "It has to be changed by means of a system, a system of checks and balances. Which means we need more Alexei Navalnys who, as the members of one coalition competing and cooperating with each other, will bring changes to our country."

Vladimir Ashurkov is a fundraiser and strategist for Navalny's campaign. He too lives under political asylum in the U.K. and is not convinced elections will ever deliver the change Russians are looking for.

"[Navalny's] main goal, as I see it, is gathering enough political capital that... the system eventually will crumble," Ashurkov said. "He will have a seat at the table when it will be decided how Russia will govern at the next stage of its development."

While Navalny is convinced he could win the election in 2018, he appears to be positioning himself for what comes next.

Becoming part of the story

One of the more unnerving moments during our time on this story was when I discovered we had become part of it.

We were in the city of Penza, in Russia's Volga Region, and I was reading Twitter when I discovered a post with a photo of our crew walking across an airport tarmac alongside Navalny.

The tongue-in-cheek caption? "Our Prince Alex Accompanied by a Full Five American Journalists. What have you achieved?"

We -- again alongside Navalny - also made it into the headlines of the local press. "Navalny Opens Penza HQ Under Americans' Watchful Eye," read one. Another article mused, "Why were (the American journalists) attracted to this news event? Someone is unlikely to travel such a distance for absolutely no reason." Still another made reference to Navalny having been spotted in Russia's regions with American diplomats. The suggestion was that we might not be journalists, that we might be somehow colluding with Navalny.

The suggestion was clear: Navalny is an American stooge. I thought it was bizarre I was being accused of meddling in Russia's election as Russia is being investigated for interfering in ours.

I asked Navalny about the news coverage. He wasn't surprised.

"Of course I saw it…They are trying to persuade people that someone is standing behind me and it's the United States," he said. "It's Kremlin's goal to try and distract me from my work and from my investigation… and trying to respond to the ridiculous allegation that I am a CIA agent."

Distrust of Americans in Russia runs just about as high as distrust of Russians in Washington, especially among the political establishment. Navalny is fluent in English and has a following among Western journalists, which makes it easy to characterize him as the West's darling, the preferred candidate to run Russia in a pro-Western, anti-Russian way. And while it looked like America and Russia might be on the cusp of a honeymoon, consider this comment from our interview in June.

"Funny that now it's more difficult for them because the Kremlin, they hated Obama, but they loved Trump. So it's more difficult to criticize me that Trump is standing behind my back," he said.

Last week, the Russian Prime Minister mocked Trump's political impotence. How quickly times change.