"We can't live here any more," Ostashenko, 31, an opposition activist like his wife, Inna Malashenko, said at the Sunday march to commemorate Nemtsov, carrying a sign that said "I'm Not Afraid." Malashenko, 24, said: "We've tried to influence things but we see that we can't."

Russia's liberal opposition is in despair after the Friday night slaying of Nemtsov in the Kremlin's shadow. While the murder elicited international condemnation and sparked the largest opposition gathering since the protests of 2011-2012 against President Vladimir Putin's rule, rank-and-file activists say the Russian leader looks stronger than ever.

Putin gained from a peace agreement that helped curb fighting in Ukraine, easing international pressure as well as the threat of new sanctions on the ailing Russian economy. At home, Nemtsov's assassination sent a chill down the spines of critics both inside and outside the ruling elite, said Gleb Pavlovsky, a former Kremlin political adviser who was sent to Ukraine by Putin to help manage Viktor Yanukovych's presidential campaign in 2004.

"There's a sense of fear across the board," Pavlovsky, who advised the Kremlin during Putin's first two terms, said by phone. "This will make people more loyal and obedient."

Putin called the "brazen" murder of Nemtsov a shame and a tragedy at a meeting with Interior Ministry officials in Moscow on Wednesday. Police must work to solve crimes with a political subtext, while the activity of extremists who seek to shake the foundations of the Russian state is becoming more sophisticated, he said.

No suspects in the killing have been identified publicly so far. "There are always suspects," Alexander Bortnikov, head of the Federal Security Service, told reporters in Moscow on Wednesday.

While the president has vowed to find the culprits, the suspicion remains that the organizers were confident of implicit support from the authorities, Pavlovsky said. Nemtsov, 55, a former deputy prime minister, was preparing to publish information about Russia's role in the Ukrainian crisis, according to his allies.

The liberal opposition has been struggling to gain traction against the backdrop of the nationalistic fervor whipped up by the conflict in neighboring Ukraine, near-record approval for Putin and government persecution. Of the movement's leaders, Alexey Navalny is serving a 15-day jail sentence for handing out pamphlets and Mikhail Khodorkovsky is in self-exile after a decade in prison.

Putin, 62, has cracked down on political foes since he was first elected in 2000, stamping out opposing voices in parliament and tightening the state's control over media. He stepped up regulations on the Internet and non-government organizations after the protests three years ago.

The pressure increased as the Ukrainian crisis deepened. State television and pro-Kremlin rallies branded anti-Putin activists agents of foreign interests. Nemtsov's allies blamed the government for creating a climate that led to the killing.

For Ostashenko and Malashenko, who worked in Navalny's failed campaign for Moscow mayor in 2013, that adds up to overwhelming odds for Putin, considering that the opposition candidate got 27 percent.

"The fact that 70 percent of people in Moscow support Putin devitalizes and demoralizes us," said Malashenko.

The drive is also gone for Alexandra Borisova, 24, a volunteer observer in the 2011 parliamentary election. While as many as 50,000 people turned out Sunday, they are just "a drop in the ocean" in a city of more than 11 million, said Borisova, a computer programmer.

"Even without the state propaganda, the attitude to Nemtsov was negative," she said, waiting with a bouquet of orange roses to file past Nemtsov's casket. "In Russia, they don't love liberals."

Vladimir Milov, a former deputy energy minister and opposition colleague of Nemtsov, acknowledged the lack of hope as he attended the politician's funeral service Tuesday.

"People who are against the authorities are really frightened and many want to leave the country," he told Bloomberg. "It's a test to see if we can survive this."

Putin's popularity remains near record levels at 86 percent, according to the Levada polling company. Another survey showed the number of people who say they have no sympathy for the opposition rising to 68 percent from 59 percent three years ago.

The opposition was counting on the economic crisis to spark a revolt on the scale of the protests of 2011-2012, the largest since the end of communism 20 years earlier.

Mikhail Kasyanov, a former prime minister who led the memorial march, vowed to pursue efforts to unseat Putin.

"We'll continue the fight for Russia to become a normal democratic country, where human rights and political freedoms are our highest values," he said Sunday.

The "strong emotional response" to the murder is unlikely to be long-lived, said Cliff Kupchan, a senior analyst at New York-based research company Eurasia Group. A "repressive" path will continue and the opposition will stay weak, he said.

A bigger risk for Putin remains the economy, hit by U.S. and European Union sanctions and the plunge in oil prices, Kupchan said.

A survey by state polling company VTsIOM showed last month that a third of Russians expect wage cuts in the next three months and a quarter fear they or family members will lose their jobs. The ruble's 46 percent slump against the dollar in 2014 eroded earnings, putting Russia on track for the biggest drop in consumption in more than two decades.

Still, the government raised its 2015 economic forecast — it now expects a 3 percent contraction — and the ruble is the world's best-performing currency in the past month, having strengthened almost 10 percent.

A stabilizing economy also helps solidify Putin's position. The notion of a palace coup by disgruntled allies, floated by some in the opposition including Navalny, is less likely than ever, said Pavlovsky, the former Kremlin adviser.

That leaves even those who feel too old to emigrate with tough choices. Igor Petrenko, 49, said he's encouraging his three adult children to get jobs abroad. While he considers opposition rallies a waste of time, Petrenko said he came along to protest Nemtsov's death out of a sense of duty.

"It's going to end badly," said Petrenko, who works in finance. "But we had to prove we did what we could."