Could Russia's "dream team" turn into a nightmare?

By Christian Lowe

MOSCOW (Reuters) - Some Kremlin-watchers have described it as a dream team: Russia's outgoing President Vladimir Putin moves into the prime minister's job and his protege Dmitry Medvedev takes over as head of state.

But many observers say a breakdown in the working relationship between the two men could destroy the stability the arrangement is supposed to safeguard.

"The existence of two rulers with two staffs is not a robust construction," said Vladimir Pribylovsky, an opposition activist and veteran political analyst.

"The entourages of the two co-rulers are already fighting with each other ... That will doubtless continue after the election."

For now at least, Putin's "operation successor" appears to be working like clockwork. Armed with an endorsement from his popular mentor, the 42-year-old Medvedev is almost certain to be elected Russia's next president in a March 2 vote.

And Putin, 55, who steps down in May, is poised to keep his hands on the levers of power by becoming prime minister in a Medvedev administration. Putin cannot stay on as president as the constitution bars him from serving three consecutive terms.

The uncertainty lies in whether the unusual arrangement will be effective: Putin is Medvedev's mentor but as prime minister he will be in a junior role answering to a younger man who has for years been in his shadow.

It is especially unusual for Russia with its tradition -- reinforced by Putin in his eight years of office -- of strong leaders who do not welcome rivals for their power.