MOSCOW - Dmitry Medvedev, a corporate lawyer tapped and groomed for the Kremlin by Vladimir Putin, was sworn in as president Wednesday under the watchful gaze of his mentor and predecessor.

As soon as the ceremony was over, just as they had planned for months, Medvedev nominated Putin for prime minister.

With the two men apparently poised to rule in tandem, Russians were left waiting with a mix of anxiety and curiosity for hints of who's really in charge: Medvedev, 42, who holds the highest job in the land, or Putin, the former KGB officer and wily politician who seems determined to keep a grip on power.

"Now it is extremely important that we together continue the course of the country, which has already justified itself," Putin told 2,000 dignitaries, referring to his years in office as a "breakthrough to new life" for Russia.

He also hinted that he regards his policies and plans as shaping Russia for decades to come, noting: "We are already formulating goals not for one or two months, but for 20 and 30 years ahead."

A sober-faced Medvedev, speaking after his longtime boss, talked of the need for rule of law and decried the corruption that has plagued Russia since the fall of the Soviet Union -- and continued to rage throughout Putin's eight-year presidency.

"We ought to achieve a genuine respect for law, to overcome the legal nihilism which seriously hampers with modern development," he said.

By midafternoon, Medvedev sent a letter to the State Duma, the lower house of parliament, nominating Putin as prime minister, then settled in to issue decrees on housing for World War II veterans and use of public lands.

The parliament is scheduled to debate Putin's nomination today.

Nobody can say for sure whether this new president is simply a fresh face to front the same ruling constellation of Putin and the power brokers who shored him up, or whether Medvedev might come into his own as a Russian leader.

"I don't even think they themselves understand how this will work," said Lilia Shevtsova, a senior associate at the Carnegie Moscow Center. "It's quite an unusual scenario."

During his rule, Putin guided Russia through years of growing wealth and influence, as skyrocketing oil prices filled the nation's coffers and allowed Moscow to throw its weight around internationally for the first time since Soviet days. Putin's admirers credit him with ushering in a new era of political stability to a weakened and traumatized country, squashing the raucous politics that defined Russia in the 1990s.