The United States will likely see a "fertile period of policy experimentation" under the new administration that takes office after the November presidential election, says Thomas E. Mann, a senior fellow at The Brookings Institution who is an expert on U.S. election campaigns.

Although key elements of the conservative movement that began in the 1980s have lost credibility, it will not mean a new liberal regime is taking over, Mann said at a Feb. 25 seminar on the U.S. presidential election, organized by the Keizai Koho Center in Tokyo.

Even if the Democrats take control of the White House and possibly expand their majority in Congress, there would be no easy answers to the tough diplomatic, economic and domestic policy challenges confronting the country, said Mann.