But Obama started to broaden his support in the last few rounds; he continued to make inroads Tuesday.

He carried Latinos in Virginia and women and lower-income voters in Virginia and Maryland; all have been vital constituencies for Clinton. At the same time, Obama continued to show tremendous strength among African Americans as he bids to become the nation's first black president; on Tuesday, he won nearly 9 in 10 black votes in Maryland and Virginia, according to exit polls conducted for a consortium of news organizations.

Obama easily bested Clinton in both states among Democrats most concerned about the economy and the war in Iraq. Clinton edged Obama among those most concerned about healthcare.

"Every week that goes by, people get a little more comfortable with him, and he gets a little stronger," said Paul Maslin, a Democratic pollster not aligned in the race. But, he cautioned, "this thing is not over."

Indeed, many Democrats confessed to a hard time deciding between the two.

"I almost didn't vote at all because if you're perfectly even, how do you choose?" said Marc Shapiro, 39, an international development consultant in Falls Church, Va., an upscale suburb of Washington. He wound up casting his ballot for Clinton.

"I went with the issue of who's ready to serve from Day One," said Shapiro, picking up on a favorite Clinton talking point.

Steve Selby, 56, a public policy professor at Michigan State University's Washington semester program, voted at the same Falls Church apartment complex. He praised Clinton as a "very strong candidate" he could happily support in November. But he backed Obama out of "a sense of change, sense of hope."

"I find the excitement among young people very encouraging," Selby said. "I think he's generated some genuine excitement that I haven't seen since I was a kid."

For the first time, Obama pulled ahead of Clinton in the delegate count, 1,223 to 1,198, according to the Associated Press. It takes 2,025 delegates to win the nomination at the party's national convention in August.

Despite the closeness of the delegate count, Obama has seized a decided edge over Clinton in momentum. He drew huge crowds over the last several days and flexed his financial muscle by handily outspending Clinton on TV advertising in Virginia, Maryland and the District of Columbia. Over the weekend, he racked up five victories -- in Louisiana, Nebraska, Washington state, Maine and the Virgin Islands -- by crushing margins.