(CNN) -- Sen. Barack Obama's wave of momentum got bigger on Tuesday. And while Sen. John McCain might not have turned the corner, he can now peek around it.
Barack Obama won the demographics on Tuesday that have been Clinton's strengths.
Obama scored a breakthrough win in the Potomac primaries by cutting into Sen. Hillary Clinton's base and winning across the demographic board.
Obama won by overwhelming numbers: In the District of Columbia, he won with three-quarters of the vote. In Maryland and Virginia, he won with two-thirds.
The Illinois senator won the women vote. He won the white vote. He won the elderly vote. He won the Latino vote. He won among every income level.
Obama's sweep of the District of Columbia, Maryland and Virginia primaries propelled him past Clinton in the race for Democratic delegates for the first time. Watch how results change the game »
Coupled with the five contests he took over the weekend, Obama's winning streak might not make next week's primary in Wisconsin a must-win state for Clinton, but a loss there could make the March 4 primaries in Ohio and Texas do-or-die for the New York senator.
Wisconsin should be tailor-made for Clinton -- a rust-belt state with a large blue-collar vote -- the same kind of voters who got her campaign back on track last month in New Hampshire a few days after Obama's stunning win in the Iowa caucuses. See CNN analysts break down results, look ahead »
But the state also has a large student population and a progressive tradition -- the kind of voters who have gone for Obama in earlier contests.
If Tuesday's trends hold, Obama could take away Clinton's strengths. She has kept pace with Obama by winning among voters age 65 and over, among women and among those making less than $50,000 a year, according to exit polls.
On Tuesday, she won none of those.
On the GOP side, McCain finally scored a breakthrough win Tuesday by winning the conservative vote in Maryland, which could be a sign that the Northern conservative vote is coalescing around him.
Although he holds a nearly insurmountable lead over former Arkansas Gov. Mike Huckabee, McCain still hasn't turned the corner with the Southern conservative vote.
McCain won the District of Columbia by an almost 3-to-1 margin and Maryland almost 2-1.
But things were different in Virginia, a state where 46 percent of Republican voters described themselves as evangelical Christians. Sixty percent of conservative voters there went for Huckabee.
McCain won Virginia on Tuesday by only a 9-point margin. See which prominent conservatives back McCain, which don't »
Although McCain is 379 delegates away from the 1,191 he needs to capture the Republican nomination, he still hasn't convinced conservatives that he should be the party's nominee.
McCain has been battered in recent weeks by talk-radio hosts over his relatively rare but high-profile departures from GOP orthodoxy.
Huckabee found the results in Virginia positive enough to use them as a reason to stay in the race, saying that they proved Republican voters still have a desire to have a choice rather than give the nomination to McCain.
However, there were positive signs for McCain going into the Wisconsin primary next week. He won among older voters in Virginia and among those who made more than $100,000 a year, signs that the populist part of Huckabee's message isn't resonating among those voters.
McCain was favored by almost 3-to-1 as being more qualified to be commander in chief, in a race in which, after the economy, national security issues are among those Republican voters list as most important to them. E-mail to a friend
CNN's Alan Silverleib contributed to this report