With 49 percent of the vote in, Obama of Illinois had 61 percent of the Democratic vote to 35 percent for Sen. Hillary Clinton of New York, MSNBC reported. He had been expected to do well in Maryland, a state where blacks are a significant part of the Democratic electorate.

On the Republican side with 37 percent of the vote counted, McCain of Arizona had 55 percent of the vote, while former Arkansas Gov. Mike Huckabee had 30 percent.

Turnout was high in spite of a winter storm that fouled roads with freezing rain. An Anne Arundel County judge ordered the polls to remain open until 9:30 p.m., 90 minutes after the scheduled closing time, because of the weather.

Some voters said they heard about the extension on the radio but were turned away because local polling places had not been notified.