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

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: 42-year-old Medvedev, 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.

In recent months, Medvedev has been a steady presence at Putin's side, following his fellow St. Petersburg native during state visits and key meetings. In one public appearance after another, both men hammered the theme of continuity, indicating that Medvedev would pick up where Putin left off. That message continued Wednesday.

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 Thursday, but the discussion is a formality. Putin has nearly finished choosing the members of the new government, the Interfax news agency reported.

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.

However, critics point out that Russia has bought the appearance of stability at the price of democracy. Putin centralized power in the Kremlin, banned people from electing their governors and clamped state control on media until virtually no independent voice remained. His government beat pro-democracy demonstrators, allowed ultranationalists free range of the streets and waged a war in Chechnya.

Perhaps nothing so neatly illustrated the authoritarian drift of Russia's government as the election of Medvedev, who was chosen by Putin and ushered to a landslide victory in an election that allowed no chance for serious opposition.

Medvedev takes over a country saddled with trouble despite its natural resources and wealth. Squalid living standards and poverty remain; the population is shrinking; international tensions are high with the West as well as with former Soviet republics such as Georgia and Ukraine. The economy is heavily dependent upon oil prices, and inflation is rising.

The prospect of a power struggle adds further uncertainty. The coming months will pit Putin's tremendous political power against the overwhelming authority granted to Medvedev by Russia's constitution. According to law, Medvedev is now in charge of foreign and domestic policy, as well as the military and security.

Still, Putin speaks of himself in epic terms and recently referred to the prime minister's post as the highest executive authority. He has agreed to head the ruling United Russia party, which controls the State Duma by a vast majority and has emerged as the de facto ruling party.

The newfound clout conferred upon United Russia by Putin's leadership was on display at the inauguration, when the audience broke into spontaneous applause for State Duma Speaker Boris Gryzlov. The other men who stepped onto the stage, the constitutional court chairman and speaker of the upper house of parliament, were not members of the party -- and were greeted with silence.

When the brief swearing-in was finished, Putin and Medvedev stood stiffly side by side, watching stone-faced as uniformed companies of the Kremlin regiment streamed past, medals and gold braid flashing, goose-stepping or trotting on horseback.

State television cameras lingered on Putin, then on Medvedev, then on both men as Putin leaned over and spoke into his prodigy's ear. Putin was no longer president, but he was very much still there. A stranger would have been unable to guess which man had just become Russia's third post-Soviet president.

For the time being, even career Kremlin watchers are stumped.

"The president is supposed to be No. 1," said Sergei Robov, director of Moscow's USA and Canada Institute. "But people don't believe that Mr. Putin can be No. 2. So we'll have to wait and see how it works."