Obama rides momentum into Wis.

MILWAUKEE -- Democrat Barack Obama swept into Wisconsin on Tuesday as huge primary victories unfolded back East. A decisive win here next week could be a breakthrough in a contest that so far has failed to produce sustained momentum for Obama or Hillary Rodham Clinton.

Clinton, coming off the resignations of two top campaign aides and eight losses since Super Tuesday on Feb. 5, is not ignoring Wisconsin. But she's focusing more attention on March 4 contests in Texas and Ohio.

The party's proportional system of allocating delegates has kept the pair in rough parity so far as they fight for the majority that will lock up the presidential nomination. But Obama's wins Tuesday in Maryland, Virginia and the District of Columbia suggested a more dramatic sense of movement.

Clinton and Obama are "inching along" on delegates, said Jean Hessburg, a former Iowa party official who directed this year's Nevada caucuses, "but the perception is that he is sweeping the country."

Analysts here say an Obama win next Tuesday in Wisconsin would be special, precisely because there's nothing special about Wisconsin. It would show his success is "not just a function of tiny states with bizarre caucus mechanisms or states that have large African-American populations. He can win in typical, average states," said Thomas Holbrook, a political scientist at the University of Wisconsin-Milwaukee.

Wisconsin has 74 delegates at stake. It will also test whether Obama can match his much improved showings Tuesday with female, Latino, senior and white voters. "If Obama can win in Wisconsin, he really looks to be unstoppable," said John McAdams, a political scientist at Marquette University.

David Plouffe, Obama's campaign manager, said the Illinois senator will continue to run as neither underdog nor front-runner. "You have to assume that you're just at a level playing field," he said. "If momentum helps attract support, great, but we don't count on it."

Clinton strategist Mark Penn said the campaign is looking ahead to March 4. As for Wisconsin, "we're going to play within the means that we have, but we clearly will have been outspent" by Obama.