orrespondent

WASHINGTON (Reuters) - Democrat Barack Obama beat rival Hillary Clinton in Mississippi on Tuesday, giving him new momentum in their increasingly nasty presidential fight as they head into the next critical showdown in Pennsylvania in six weeks.

The win for Obama, who would be the first black U.S. president, extended his lead over Clinton in pledged delegates to the August nominating convention. The Illinois senator also won Saturday in Wyoming.

Clinton revived her hopes in the Democratic race last week with big wins over Obama in Ohio and Texas, prolonging their bitter Democratic fight for the right to face Republican John McCain in November's presidential election.