More US Democrats prefer Barack Obama over Hillary Rodham Clinton to be the party's presidential nominee, said a national poll released on Monday.

According to the poll by CNN and Opinion Research Corporation, about 52 percent of registered Democrats picked the Illinois senator as their choice for the November national election, while 45 percent supported the New York senator.

Among 1,019 Americans surveyed by telephone from March 14 to 16, 45 percent said they are more enthusiastic about Obama's victory in the presidential nominee race, and 38 percent expected Clinton' s win.

CNN polling director Keating Holland said Obama's biggest support came from men, younger voters and Democrat-inclined independents, while Clinton showed bigger appeal for women, older voters and whites.

The two presidential candidate are still caught in a close tie after most states and territories held their Democratic primaries and caucuses, with Obama's slight lead over Clinton in the number of delegates who would vote at the nomination convention.

Nearly 800 Superdelegates, who are taken by Democratic lawmakers, top elected state officials and members of the party's national committee, have been considered to play a decisive role in determining the presidential nominee.

About 49 percent of the polled registered Democrats said the Superdelegates should base their votes on their view of who would be the best candidate, and 46 percent believed that Superdelegates should follow the results of the primaries and caucuses.

(Xinhua News Agency March 18, 2008)