Up against this colossus went Ms. Safronova, 53, a former Kremlin supporter who grew increasingly frustrated with the country’s political stagnation and decided to do something about it this year. She mounted her campaign for regional assembly, and worked to transform A Just Russia in Novosibirsk, Russia’s third largest city.

From the start, Ms. Safronova realized that the odds were against her.

She dressed like a corporate lawyer on the campaign trail, slogging through the mud of a dairy farm in the city suburbs in high heels. But the truth was that she was a widow with little money who lived with her mother, son and granddaughter in a threadbare housing project that looked as if it had not been renovated since Brezhnev’s time. She had long blond hair that she sometimes styled in a classic Slavic peasant braid, as if to hark back to her rural roots.

An economist by training, she had made many enemies as regional leader of a group called the Public Anticorruption Committee and, before that, as an advocate for small business in Novosibirsk. She expected that the governing party would be infuriated with the regional branch of A Just Russia. And so she was not surprised when she received menacing phone calls from people who would not identify themselves.

“They say, if I don’t end my campaign, they will kill me,” she said.

Still, she thought that even if she did not win, she could secure a high enough percentage of the vote to help prove that Russia had a viable new opposition at the regional level.

If United Russia went unchallenged, she insisted, then Russia would end up like the Soviet Union: foundering under the corrupt and incompetent reign of a single party.

“We are hoping that a massive number of people will come out on Election Day and declare that they will not take this anymore,” she said shortly before the voting. “We are striving to create a true multiparty system, a real democracy in Russia.”