But lately the tandem has begun to hiccup and backfire. It is impossible to say whether trust has broken down between the two men, one of whom will increase his power in next spring’s presidential election. But a universe of officials, businessmen and political hangers-on — uncertain whether to show loyalty to one man, the other or both — has “spent the whole last month on the verge of a nervous breakdown,” the economist Vladislav L. Inozemtsev wrote last week in the newspaper Moskovsky Komsomolets.  Mr. Putin invented the arrangement in 2008 when term limits prevented him from seeking the presidency again, and it is largely his choice whether to continue it. He has tried to put a lid on speculation even while working to delay an announcement until the fall on who the presidential candidate will be, but he may be too late.  Winston Churchill compared Kremlin power struggles to bulldogs fighting under a carpet: “An outsider only hears the growling, and when he sees the bones fly out from beneath, it is obvious who won.”  That dynamic has returned in the past few weeks, as minor political figures began thrusting rumors into the public domain. Take the case of Konstantin F. Zatulin, a member of Parliament for the governing party, United Russia, which stripped him of a committee post after he vocally supported Mr. Putin’s views on Libya over the president’s, effectively driving a wedge between the two. He then began saying publicly that Mr. Medvedev had broken his agreement with Mr. Putin and was trying to undermine him.  “The oldest story in history has occurred here: having received grandiose authorities, a young president, and to a greater extent his inner circle and his family,” are determined to keep them, Mr. Zatulin said in an interview in his ornate office. He said that Mr. Medvedev was backed by powerful industrialists, known as oligarchs, who hoped to reclaim the influence they lost under Mr. Putin.  “I think they are much more comfortable with a weak president than a strong one, and have found a person they can manipulate,” Mr. Zatulin said.  He said distrust between the teams was so high that the tandem was unlikely to continue after the elections, and that Mr. Medvedev might use the single advantage he has over his mentor. “I cannot exclude that some of Medvedev’s advisers consider that Medvedev, in order to win, should fire Putin from the position of prime minister,” Mr. Zatulin said. “I can’t confirm it, but it would be strange if they had not considered this possibility.”  Not long after Mr. Zatulin’s punishment was made public, an oddly symmetrical story appeared in the press. This time, it was Gleb O. Pavlovsky, a political consultant, who said that he had been rebuked for saying that Mr. Putin should not return to the presidency. He said that officials in the Kremlin had complained for many months about his comments, which violated the unspoken order to “say nothing about a candidate until everything is decided.” In mid-April they severed a 15-year relationship. “Putin and his team are very nervous about this kind of statement, probably more touchy than Medvedev’s team,” Mr. Pavlovsky said.  He said that there was no personal split between the two men — “I can confirm this,” he said — but that the tandem had been carefully constructed to maintain balance, and that neither man’s team was strong enough to end the standoff. He said that Mr. Putin began considering a return to the presidency because of “a virtual fear that some awful liberals will come to power” and weaken the strong state that Mr. Putin had built.  “Where are those liberals? They don’t exist,” Mr. Pavlovsky said. “This is the problem. I’ve been hearing about these liberals for 20 years.”  For now, his main complaint is that paralysis over the candidate makes it impossible to get to work on substantive issues, like what path Russia should take after the elections. “It’s absurd; debates are necessary today” about the next president’s platform and his team, Mr. Pavlovsky said. “It’s very difficult to make up a team without having a leader. It’s like learning how to swim in a dry pool.”  In these interviews, as in all of Russian politics, it is difficult to say what is real and what is artificial. Neither Mr. Zatulin nor Mr. Pavlovsky is a member of the leaders’ inner circles, and their motives are unclear. Mr. Zatulin lost a powerful ally in September when Yuri M. Luzhkov was driven from his post as Moscow’s mayor on the president’s orders. Mr. Pavlovsky, meanwhile, has a 15-year résumé of virtuosic political gamesmanship.  But it is clear that the public gap between Mr. Putin and Mr. Medvedev has widened. First, they staked out different positions on NATO’s operation in Libya, which Mr. Putin has passionately condemned. When Mr. Medvedev told Chinese television that the presidential candidate would be announced shortly, Mr. Putin contradicted him, making it clear he preferred to wait as long as possible.  History suggests that could be quite a long time. Boris Yeltsin announced his resignation on Dec. 31, 1999, a few days after parliamentary elections; in 2007, Mr. Putin identified Mr. Medvedev as his successor on Dec. 10, a few days after parliamentary elections. This year’s parliamentary elections are scheduled for Dec. 4.  In the meantime, Moscow’s political circles will be watching for bulldogs under the rug.  Mr. Putin stoked a new round of speculation on Friday when he announced the creation of a nationwide “popular front,” which some saw as laying the groundwork for a possible presidential run. Mr. Medvedev has called a rare news conference for May 18, to the same effect.  Prolonged tension risks setting off a major split within the elite, said Dmitri K. Simes, a veteran Russia watcher who heads the Center for the National Interest, a Washington-based think tank. He returned from a recent trip to Moscow struck by the shift in the political atmosphere, now rife with distrust. “Never forget the number of people who are playing double games,” he said. “People run around saying one thing in the morning and another thing in the afternoon.”
The division of authority between the two leaders has seemed to work smoothly for the past three years, but it has recently shown signs of breaking down.