WASHINGTON — Barack Obama powered past Hillary Rodham Clinton in the race for Democratic delegates yesterday with outsized primary victories in Maryland, Virginia and the District of Columbia.

The Associated Press count of delegates showed Obama with 1,212. Clinton had 1,191, falling behind for the first time since the campaign began. They need 2,025 to win the nomination.

Republican front-runner John McCain won all three GOP primaries, adding to his virtually insurmountable lead in delegates for his party's nomination.

Obama's victories were by large margins — he gained about 75 percent of the vote in the nation's capital and nearly two-thirds in Virginia. In Maryland, he was winning close to 60 percent.

He succeeded by winning over many of the voters who form the core of Clinton's political base, according to an exit survey conducted for The Associated Press.

Clinton has been strong among traditional Democratic base voters, such as Hispanics and working-class whites. Obama has run strongest among young people, independents, affluent voters and blacks.

But Obama narrowly defeated Clinton among white voters in Virginia, 52 percent to 47 percent, while Clinton won with that group in Maryland by just 10 percentage points.

Even white women were beginning to move toward the Illinois senator — Clinton won nearly 60 percent of their votes, a much lower percentage than in contests past. Clinton has based her candidacy in large part on her appeal to white women.

"Tonight we're on our way," Obama told cheering supporters in Madison, Wis. "But we know how much further we have to go," he added, celebrating eight straight victories over Clinton, the former first lady now struggling in a race she once commanded.

By contrast, Clinton was attempting to retool her campaign in the midst of a losing streak. Her deputy campaign manager resigned, the second high-level departure in as many days.

Campaigning in Texas, where she hopes to triumph on March 4, she said she was looking ahead, not back.

"I'm tested, I'm ready. Now let's make it happen," she said.

After his victories were affirmed, McCain congratulated Mike Huckabee, his sole remaining major rival and a potential vice presidential running mate. Then McCain turned his focus on the Democrats.

"We know where either of their candidates will lead this country, and we dare not let them," he told supporters in Alexandria, Va. "They will paint a picture of the world in which America's mistakes are a greater threat to our security than the malevolent intentions of an enemy that despises us and our ideals."

CLOSE VICTORY

McCain's victory in Virginia was a relatively close one, the result of an outpouring of religious conservatives who backed Huckabee.

Four in 10 Republican voters said they were born again or evangelical Christians — twice as many as called themselves members of the religious right in 2000 — and nearly 70 percent of them supported Huckabee, an ordained Baptist minister.

Virginia voters could vote in either primary in their state. In a twist, Huckabee was running slightly ahead of McCain among independents, who cast about a fifth of the Republican votes there.

There were 113 delegates at stake in the three GOP races.

The AP count showed McCain with 789 delegates. Former Massachusetts Gov. Mitt Romney, who dropped out of the race last week, had 288. Huckabee had 241 and Texas Rep. Ron Paul had 14.

It takes 1,191 delegates to clinch the Republican nomination, and McCain appears to be on track to reach the target by late April.

"Until someone gets that magic number, we still have an election process and there is no nominee," Huckabee said. "And once that happens, we've got a nominee, it's time to rally around him."

STILL UNCERTAIN

The Democratic race was the definition of unsettled, with Clinton surrendering her long-held lead in delegates, having shed her campaign manager and lent her campaign $5 million in recent days, and facing defeats next week in Wisconsin and Hawai'i.

In addition to his usual strong showing among young voters, Obama also was running about even among those older than 65, a group Clinton usually dominates.

"This is the new American majority. This is what change looks like when it happens from the bottom up," Obama said last night.

As the votes were counted in her latest setbacks, her deputy campaign manager stepped down. Mike Henry announced his departure one day after Patti Solis Doyle was replaced as campaign manager with Maggie Williams, a longtime confidante of the former first lady.

Clinton hopes to respond with victories in Texas and Ohio on March 4, states where both candidates already have begun television advertising.

Since last week's Super Tuesday contests in 22 states, Obama had won a primary in Louisiana as well as caucuses in Nebraska, Washington and Maine, all of them by large margins.

Obama has campaigned before huge crowds in recent days, and far outspent his rival on TV advertising in the states participating in the regional primary in Maryland, Virginia and the District of Columbia.

With Clinton facing a series of possible defeats, and Obama riding a wave of momentum, the two camps debated which contender is more likely to defeat McCain in the general election.

An Associated Press-Ipsos poll found Obama with a narrow lead over the Arizona senator in a potential match-up, and Clinton running about even.

"We bring in voters who haven't given Democrats a chance" in the past, said Obama pollster Cornell Belcher, citing support from independents.

Mark Penn, Clinton's chief strategist, countered that she holds appeal for women voters and Hispanics.

"Hillary Clinton has a coalition of voters well-suited to winning the general election," he said.

Based on McCain's speech last night, he seems to think Obama will be his opponent in the fall. He aimed much of his rhetoric at the Illinois senator's message of hope and optimism.

"Hope, my friends, hope is a powerful thing," said McCain. But he added, "To encourage a country with only rhetoric rather than sound and proven ideas that trust in the strength and courage of free people is not a promise of hope. It's a platitude."