Obama sweeps Clinton in Maryland, Va., D.C.

WASHINGTON - Sen. Barack Obama was projected to sweep Sen. Hillary Rodham Clinton in Tuesday's primaries in Maryland, Virginia and the District of Columbia, NBC News said, giving him an unbroken string of victories since Super Tuesday.

On the Republican side, Sen. John McCain defeated former Arkansas Gov. Mike Huckabee in all three contests.

The three wins — which came by substantial margins — helped Obama build on the delegate lead that he has gained in the past week in NBC News' count.

“Tonight we’re on our way,” Obama told cheering supporters Tuesday night in Madison, Wis. “We now have won east and west and north and south and across the heartland of this country we love.”

Clinton was said to be depending on victories in the big states of Ohio and Texas next month in her struggle to keep up in a race she once commanded.

She campaigned in El Paso, Texas, on Tuesday night, telling supporters: "I'm tested, I'm ready — let's make it happen."

Clinton didn't mention Tuesday's results, but there were lingering signs of the disquiet in her campaign.

Clinton's campaign manager resigned over the weekend, and it was learned Tuesday that deputy campaign manager Mike Henry resigned Monday. A source told NBC that Henry was leaving to allow new campaign manager Maggie Williams to organize her own team.

Obama makes some inroads
With his victories Tuesday, Obama showed signs of eating into Clinton's voter base. He had nearly two-thirds of the vote in Virginia, about 60 percent in early returns in Maryland and 75 percent in the District of Columbia.

Video Obama: ‘This is what change looks like’ Feb. 12: Sen. Barack Obama, D-Ill, addresses supporters after winning the Potomac primaries saying, ‘This is the new American majority. This is what change looks like when it happens from the bottom up.’ MSNBC

Interviews with voters leaving the polls showed Obama split the white vote with Clinton in Virginia, though she won it by 10 percentage points in Maryland. She won a majority of white women in both states, though by less than she is accustomed to. He won among white men in Virginia, and they split that vote in Maryland.

In addition to his usual strong showing among young voters, Obama was also running about even among those over 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 at the campaign rally in Wisconsin, which holds its primary next Tuesday.

Video Chuck Todd talks numbers Feb. 12: NBC's Chuck Todd offers political analysis on the latest exit polls. Nightly News

Obama, who would be the first black president, also won the votes of nine in 10 black voters in Virginia, where they were about a third of the electorate, and his won almost as many in Maryland.

And Obama was winning 66 percent to 33 percent among independents, who made up a fifth of the Democratic electorate in Virginia. He did even better — 70 percent to 26 percent — among Republicans, who made up 8 percent of the Democratic vote. Virginia held the two parties' primaries on the same day for the first time and voters can cross party lines in primaries there.

Virginia Gov. Tim Kaine said in an interview on MSNBC that the makeup of the Democratic electorate bore out his belief that Obama could strongly attract independent voters in November in Virginia, which has been solidly Republican in previous presidential elections.

“The results tonight suggest that we’re going to be very razor-thin competitive in November,” said Kaine, who has endorsed Obama.

Clinton looks to Texas
The Illinois senator won a string of contests in all regions of the country over the weekend, routing Clinton in a Louisiana primary as well as caucuses in Nebraska, Washington state, Maine and the Virgin Islands.

Obama's latest victories put more pressure on Clinton, who faces possible defeats next week in Wisconsin and Hawaii. Obama led Clinton on Tuesday night, with 1,078 delegates to her 969, according to NBC News.

Video Clinton: ‘Let’s make it happen’ Feb. 12: In a speech in El Paso, Texas, Hillary Clinton tells supporters, ‘I’m tested, I’m ready – Let’s make it happen.’ MSNBC

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

“Clearly, coming out of Super Tuesday, it was expected that Sen. Obama would take the states he has taken,” said Lisa Caputo, a senior adviser to Clinton.

Caputo acknowledged in an interview on MSNBC that the campaign was “focusing its resources on the big states with the big delegate counts, because let’s remember, it’s all about the delegates.”

“All eyes are on the states of Texas and Ohio,” she said. “She absolutely has to win Ohio and Texas, and probably Pennsylvania.”

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