What the government of Prime Minister Vladimir Putin has been lacking is a respectable opposition, in the sense of one that looks legitimate to business people and intellectuals and foreign investors and Western governments.

So earlier this year Putin’s men at least implicitly let it be known that Mikhail Prokhorov, the billionaire owner of the New Jersey Nets, would be a good choice to take over the floundering Right Cause party.

Detractors called Prokhorov, who had no political experience, and his party “Kremlin puppets.” Others saw Right Cause as a fig leaf for a system that is, in fact, ruthless and monolithic. But Prokhorov himself began to get interested in the idea of politics as something genuine.

And in the space of just a few months, the people around Putin began to have second thoughts about him. The party met this week and Prokhorov announced that the Kremlin was trying to take it over, the way it tries to take over independent businesses. But instead of deploying the tax police, he said, in this case it was packing the convention with fraudulent delegates. Some thought this was all just part of a show to give him the appearance of independence, but on Thursday he angrily stalked out, the party expelled him, a rump formed and the whole project collapsed.

Some party members reported that the Kremlin had promised them this week they would receive seven percent of the popular vote in this December’s parliamentary elections, assuring the party of representation in the Duma — but only if they demonstrated their obedience. (No one expressed any surprise that the Kremlin would be able to fine-tune vote totals; for that matter, an August poll by the Levada Center here found that 54 percent of Russians think the elections will be “simulated.”)

But Prokhorov took a stand. The pretext was his alliance with Yevgeny Roizman, a nationalistic anti-drug crusader from Yekaterinburg. Kremlin political strategist Vyacheslav Surkov wanted Roizman gone, and more significantly he wanted to show Prokhorov who was the boss, political analyst Andrei Piontkovsky said Thursday. Prokhorov balked.

So the party ruptured, and there’s clearly no way to put it back together.

“I do not plan to quit politics,” Prokhorov said, after he had moved with his supporters to a hall at the Russian Academy of Sciences. Calling Right Cause a “bought party,” he said, “All my associates and all those who support me — I am urging you to leave this puppet Kremlin party.”

If there’s one thing that democrats and Kremlin strategists agreed, it’s that Prokhorov actually has no future in Russian politics. “Mediocrity has again won a victory,” Sergei Mitrokhin, a leader of a small but real opposition party called Yabloko, told the Interfax news agency. “He must understand that no one will allow him to form a new party.”

But the bigger loser might be Putin.

For four years President Dmitry Medvedev was the liberal face of the regime, but he has used up his effectiveness in that role, Piontkovsky said. So Right Cause “was a very serious project of the Kremlin.” Putin needs a liberal hope, to keep liberal opposition paralyzed.

“It was a clever project. A lot of liberals believed in it,” Piontkovsky said. “But what happened today destroyed this project. The Putin regime has lost its liberal clothes for the next six years.”