A former law professor who has spent much of his career as a behind-the-scenes bureaucrat, Mr. Medvedev showed a wide-ranging knowledge of foreign and domestic issues, confidently answering questions for 90 minutes without notes and speaking at length without stumbling. The president, who is 42, spoke only in Russian but did not need an interpreter to understand questions posed in English.

Mr. Medvedev provided no glimpses of disagreements with Mr. Putin on policies or strategy, though their stylistic differences were readily apparent. Whereas Mr. Putin occasionally responds to questions with blunt retorts or salty language, Mr. Medvedev tends to offer demurrals and then to engage in a kind of academic discussion of issues.

As he has many times in recent weeks, Mr. Medvedev championed his proposals to reduce corruption, which he acknowledges is endemic in Russia. He was then asked whether he believed that corruption could be beaten back, considering that the country’s political system is dominated by a single party, Mr. Putin’s United Russia.

“A system that was built on the idea that one party holds all the truths demonstrated its weakness 20 years ago,” Mr. Medvedev said. “It failed to cope with new challenges and ceased to exist. That’s why, to ensure the competitive ability of our country on a global scale, we must make use of political competition, among other things. But it must be sensible. This is to say, competition, correctly built.”

Mr. Medvedev indicated that he would not get involved in the case of Mikhail B. Khodorkovsky, the former oil oligarch and Putin opponent convicted of financial crimes and sent to a Siberian prison. The authorities have recently brought new charges against Mr. Khodorkovsky, while his lawyers have mounted a campaign for his release.

Some political analysts have described Mr. Medvedev as more liberal than Mr. Putin and others in the Kremlin, in part because Mr. Medvedev did not serve in the security services. (Mr. Putin is a former K.G.B. agent who was head of its successor agency, the F.S.B.)

Mr. Medvedev often says his background as a lawyer plays a crucial role in his worldview, and when he was asked about his reputation, he returned to that theme. He said that when he was a student, he learned of the importance of the law, and of the right to private property. He said he also realized that there needed to be a struggle in Russia against what he has termed “legal nihilism.”