WASHINGTON-- --Democrat Barack Obama and Republican John McCain swept the Potomac primaries yesterday after voters endured ice-slick roads and snow flurries to cast ballots in the most competitive presidential primary contest in decades.

For Obama, the triumphs extend the momentum built after last week's Super Tuesday contests. The Illinois senator has earned consecutive wins in eight contests since then, eclipsing Sen. Hillary Clinton of New York in the chase for delegates for the first time.

"We won the state of Maryland. We won the commonwealth of Virginia," Obama said last night during a rally in Wisconsin, which votes next week. "And though we won in Washington, D.C., this movement won't stop until there is change in Washington, D.C."

A count of delegates showed Obama with 1,186 and Clinton with 1,181, according to the Associated Press; 2,025 are needed to win the nomination.

It is becoming increasing clear that the eventual nominee will likely need the support of hundreds of party insiders and elected officials known as "superdelegates" to reach that total.

Exit polling showed that Obama did particularly well in Maryland, where bad weather caused a judge to order polls to remain open until 9:30 p.m., 90 minutes past their scheduled close.

Obama won in all areas of the state, including Baltimore, the city's suburbs and the Washington region. Eight of 10 Marylanders said the country was ready for a black president, the polls said, and Obama won the votes of two-thirds of them.

He carried rural and urban voters and earned majorities among those with and without college degrees -- making inroads with the less wealthy and less educated, groups among which Clinton had been basing her support elsewhere.

After a string of losses and a cash crunch, Clinton's campaign is focusing resources on Texas and Ohio, looking for victories there March 4 to try to regain her delegate lead. The campaign also confirmed yesterday that its deputy manager was leaving.

"This election could not be more important. And there are some real differences that have to be sorted out by the voters of Texas," Clinton said last night at a rally in El Paso, during which she made no mention of yesterday's primaries.

Prince George's County State's Attorney Glenn F. Ivey, an Obama supporter, predicted that the Illinois senator would have enough campaigning time to erase any remaining Clinton advantage in the March 4 states.

"He got a hat-trick tonight in the Chesapeake primaries," Ivey said. "He's got the momentum. He demonstrated he can win in a variety of states in all different types of categories. He looks like he can start dominating this."

The McCain victories solidified his position as the presumptive nominee, despite a strong showing by former Arkansas Gov. Mike Huckabee in Virginia, which illustrated continuing concern about McCain's conservative credentials.

McCain's campaign received a further boost when President Bush's top fund-raiser agreed yesterday to join the Arizona senator's effort.

Huckabee received more than 40 percent of the Republican vote in Virginia. He was the heavy favorite among the third of Republican voters who called themselves "very conservative," as well as the 46 percent of the electorate who were evangelical Christians, exit polls show.

The McCain campaign said it would continue to try to win over those voters.

"As I have done my entire career, I will make my case to every American who will listen," McCain said at his Alexandria, Va., campaign headquarters last night. "I will not confine myself to the comfort of speaking only to those who agree with me. I will make my case to all the people. I will listen to those who disagree. I will attempt to persuade them."

Secure enough to look ahead to a general election match, McCain took veiled swipes at Obama last night, saying that "to encourage a country with only rhetoric rather than sound and proven ideas ... is not a promise of hope. It is a platitude."

For Huckabee, the losses ended a streak of his own. He won over the weekend in Kansas and Louisiana and came close in Washington.

Huckabee said last night that he would "march on" so voters can continue to have a choice.

"If anything we are doing is important, it is recognizing that people in the states who have not yet had their elections have as much right to an election as all these folks who are front-loaded for either Super Tuesday or prior to that," he said.

Despite cold temperatures throughout the day and treacherous roads and snarled traffic in the evening, the Maryland Board of Elections was projecting voter turnout of 39 percent -- an impressive showing compared with recent presidential primary elections but not a record.

The well-organized Obama campaign used the extra time to extend its aggressive telephone outreach, continuing to urge voters to get to the polls in the final minutes of voting.

The turnout estimate was based on key precincts in the state that saw increased voter activity, said Ross Goldstein, chief deputy administrator at the state elections board. Democrats were projected to vote about 42 percent, while Republican turnout was expected to be about 29 percent, Goldstein said.

Two competitive congressional races also drew voters to the polls in Maryland.

In Maryland's 1st District, which includes the Eastern Shore and stretches northwest through Cecil, Harford and Baltimore counties, Republican incumbent Rep. Wayne T. Gilchrest lost a vigorous primary challenge to state Sen. Andy Harris. Sen. E.J. Pipkin was also in a race whose incessant television ads and mailings crowded out the presidential contest.

In the 4th District, Rep. Albert R. Wynn lost to challenger Donna Edwards, whom he narrowly defeated two years ago.

In most election years, the candidates have by now locked up the delegates necessary to secure their party's nomination, so Maryland's presidential primaries haven't mattered much. But the remarkably unsettled nature of this year's election pulled the full force of national campaigns into the region.

A barrage of advertisements and candidate appearances over the past few days gave political leaders what they hoped for when they decided last year to band together for a Mid-Atlantic voting day.

Because Democratic delegates are awarded in proportion to vote totals, both Obama and Clinton were expected to pick up delegates yesterday, when 168 delegates were awarded in the three jurisdictions. Obama was hoping to do well enough in Baltimore, Prince George's and Montgomery counties and Northern Virginia to amass a solid lead.

There were 116 GOP delegates available yesterday, and McCain, with 729 delegates heading into the Chesapeake primaries, was well on his way to the 1,191 needed for nomination.

After spending the past several days barnstorming through the region, the top presidential contenders were looking past the Potomac primaries even before votes were counted.

Voting was heavy in many parts of Maryland early in the day, before weather became troublesome. Voters began lining up at 6:30 a.m. at Randallstown High School, where workers let them inside early to keep them warm before polls opened.

"The line has been unbelievable," said Alease Ferguson, the chief Republican election judge at the precincts there. "People want to be a part of this history, no matter who it is, Obama or Hillary."

Jessica Douglas, 17, a senior at Notre Dame Preparatory School, said she was supporting Obama because she was "a big fan of the way he thinks and presents himself."

If Obama were not on the ballot, she said, she wouldn't be interested in the presidential race.

Carol Weber, 63, a retired clerical worker for Baltimore County schools, said she was voting for Clinton because "I think it's time for a woman. I think a woman is more detail-oriented than a man, and I think a woman could run the country better."

Don Mason, 81, a self-described "Reagan Democrat" from the Eastwood section of Baltimore County, said he voted yesterday for Obama because he found Clinton "super liberal," but he planned to vote Republican in November.

"No doubt I will vote for McCain," said Mason, a retired Sparrows Point engineer and a former county councilman.

david.nitkin@baltsun.com

Sun reporters Brent Jones, Larry Carson, Gina Davis, Jennifer McMenamin, Tyeesha Dixon, Chris Guy and Gadi Dechter contributed to this article.