If you read Julia Ioffe's recent piece on Yuri Luzhkov, you know that Moscow's long-time mayor is currently embroiled in a serious fight with the Kremlin. A dispute between Luzhkov and the administration of President Dmitry Medvedev over control of a highway project linking Moscow and St. Petersburg has sparked an uncharacteristically public conflict over control of Moscow itself.

But the real problem it exposed is that Luzhkov plays in his own ballpark in a country where the Kremlin wants monopoly control of politics. Luzhkov was already mayor of Moscow in June 1992 when Medvedev was still a junior staffer (working for Vladimir Putin) inside the St. Petersburg mayor's office. Over the years, Luzhkov has constructed the only patronage network in Russia that exists (at least partially) outside the Kremlin's "power vertical," the carefully constructed top-down hierarchy that ensures that every provincial official answers directly to someone who answers to senior officials in Moscow. Luzhkov's control of Moscow is possible only because Russia is still run by personalities rather than institutions, and because he remains the key player in a network of political and commercial relationships that impose order on Russia's most important city.

Over the years, Russia's power players have kept Luzhkov on a relatively long leash -- with the occasional tug to remind him the leash is still there. Yet, given the tone of some of his recent public complaining, someone in the Kremlin has decided that enough is enough. State-dominated television stations have run a series of surprisingly harsh attacks on Luzhkov's character and integrity, a clear signal in today's Russia -- as in the Soviet Union -- that a political career is coming to an end.

It's not a surprise that Luzhkov's time has come. His recent criticism of Medvedev is just the latest act of gross insubordination in a system where hierarchy is everything. Medvedev has the power to fire Luzhkov on the spot.

So why hasn't Russia's president already retired Moscow's mayor? Because he doesn't yet have permission from Russia's prime minister.

Vladimir Putin has not yet gone on camera to address this fight directly, though the televised assault on Luzhkov could not have come without his explicit blessing. But there are probably two reasons why Putin hasn't yet given Medvedev the nod to remove Luzhkov.

First, with parliamentary elections coming late next year and a presidential vote in the first few weeks of 2012, Putin wants to preserve the appearance of a united Russia. Luzhkov looks on Medvedev with the disdain that guys like Jimmy Hoffa reserve for guys like Robert Kennedy. Allowing Medvedev to summarily fire him might provoke Luzhkov to make a stink that can't be contained. Better to allow him to resign, as long as he does it soon.

Second, though Luzhkov WILL be pushed aside -- the media assault on him commits the Kremlin to action -- Putin needs time to co-opt enough of Luzhkov's allies and clients to ensure that things remain quiet as the mayor is replaced.

The larger problem for Russia is that Moscow's mayor has demonstrated publicly that the president can't take a tough political decision without a nod from the prime minister, further undermining the fiction that Putin and Medvedev are governing partners. This episode pushes Medvedev much closer to lame-duck status, and Putin will have fewer options when it comes to the 2012 presidential election.

It's one more sign that only Putin has the chops to play Russia's headline role.

Ian Bremmer is president of Eurasia Group and author of The End of the Free Market: Who Wins the War Between States and Corporations?