WASHINGTON - A split decision written across a vast electoral map has locked Barack Obama and Hillary Rodham Clinton in a protracted struggle for the Democratic presidential nomination, while John McCain goes forward as the clear favorite of the Republican race.

McCain, whose campaign once verged on collapse, piled up more delegates than his two rivals combined, pushing over the halfway mark on what's needed to clinch the nomination. His victories stretched from New York to California, the biggest prize. Still, Mitt Romney in the West and Mike Huckabee in the South proved to be go-to candidates for conservatives, and they vowed to press forward.

Clarity of any sort eluded the Democrats as campaigns turned to the next rounds. On Saturday, Louisiana and Washington state hold two-party contests while Nebraska Democrats and Kansas Republicans make their picks. Then comes a larger series of two-party primaries in Maryland, Virginia and the District of Columbia on Tuesday.

More than 168 Democratic delegates are at stake Tuesday, a sizable prize in two states and a district that are normally afterthoughts in nomination contests. Clinton, who plans to campaign in Virginia on Thursday, has been endorsed in Maryland by Gov. Martin O'Malley and Sen. Barbara Mikulski; Obama is backed by Virginia Gov. Tim Kaine, and is expected to do well in largely black D.C.

"Senator Clinton has a lot of friends in Virginia," Kaine said in an interview, but "we're feeling pretty good" about Obama's Virginia chances. Republicans will award 116 delegates in the trio of races dubbed the Potomac Primary.

Exit polling indicated Obama and Clinton were each getting support from almost half of white men, marking a big improvement for the Illinois senator. Former Sen. John Edwards' departure from the Democratic race last week may have helped Obama with white males, who made up more than a quarter of Tuesday's Democratic voters from coast to coast.

More than four in 10 women and about the same number of whites also were supporting Obama. That represented a gain for him from most previous Democratic nominating contests this year, although he still trailed Clinton by more than 10 percentage points in both categories, a significant gap in a two-person race.

Democrats celebrated heavy turnout in several of their races and hoped they could bottle that electricity until the presidential campaign in the fall. As one measure, Clinton managed to get more votes in Minnesota than all that were cast in the 2004 Democratic caucuses in that state, despite her running a distant second to Obama.

Huckabee, who posted five Southern victories after being practically counted out of the contest, demurred when asked Wednesday if he'd be an irresistible running mate for McCain, the opponent he likes. "I still want to be the irresistible choice to be the president," he said on CBS' "The Early Show."

Despite his strong night, Huckabee trails both McCain and Romney in the delegate count.

Obama won 13 Super Tuesday states; Clinton, eight plus American Samoa. Clinton scored the advantage in delegates, bring her total to 845 to Obama's 765, by the latest accounting. The road ahead was long for the Democrats: It takes 2,025 delegates to claim their nomination.

Delegate tabulations continued Wednesday, possibly longer, and the victor in one race remained unsettled — the Democratic caucuses in New Mexico.

Clinton won the biggest state, California, capitalizing on backing from Hispanic voters. Obama scored victories in Alabama and Georgia on the strength of black support, and won a nail-biter in bellwether Missouri.

McCain's own victory in California dealt a crushing blow to his closest pursuer, Romney, a former Massachusetts governor.

"We've won some of the biggest states in the country," the Arizona senator told cheering supporters at a rally in Phoenix, hours before California fell his way. An underdog for months, he proclaimed himself the front-runner at last, and added. "I don't really mind it one bit."

In the competition that counted the most, the Arizona senator had 613 delegates, to 269 for Romney and 190 for Huckabee in incomplete counting. It takes 1,191 to win the GOP nomination.

Neither Democrat could plausibly claim an overall victory and didn't try.

"I look forward to continuing our campaign and our debate about how to leave this country better off for the next generation," Clinton said.

Obama told a boisterous election night rally in Chicago, "Our time has come. Our movement is real. And change is coming to America."

Polling place interviews with voters suggested subtle shifts in the political landscape.

For the first time this year, McCain ran first in a few states among self-identified Republicans. As usual, he was running strongly among independents. Romney was getting the votes of about four in 10 people who described themselves as conservative. McCain was winning about one-third of that group, and Huckabee about one in five.

Overall, Clinton was winning only a slight edge among women and white voters, groups that she had won handily in earlier contests, according to preliminary results from interviews with voters in 16 states leaving polling places.

Obama was collecting the overwhelming majority of votes cast by blacks — a factor in victories in Alabama and Georgia.

Clinton's continued strong appeal among Hispanics — she was winning nearly six in 10 of their votes — was a big factor in her California triumph, and in her victory in Arizona, too.

McCain, the early Republican front-runner whose campaign nearly unraveled six months ago, won in California, New York, New Jersey, Connecticut, Missouri, Delaware and his home state of Arizona — each of them winner-take-all primaries. He also pocketed victories in Oklahoma and Illinois.

Huckabee, the former governor of Arkansas, won a series of Bible Belt victories, in Alabama, Georgia and Tennessee as well as his own home state. He also triumphed at the Republican West Virginia convention, and told The Associated Press in an interview he would campaign on. "The one way you can't win a race is to quit it, and until somebody beats me, I'm going to answer the bell for every round of this fight," he said.

Romney won a home state victory in Massachusetts. He also took Utah, where fellow Mormons supported his candidacy. His superior organization produced caucus victories in North Dakota, Montana, Minnesota, Alaska and Colorado, and he, too, breathed defiance. "We're going to go all the way to the convention. We're going to win this thing," he told supporters in Boston.

Democrats played out a historic struggle between two senators: Clinton, seeking to become the first female president, and Obama, hoping to become the first black to win the White House.

Clinton won at home in New York as well as in California, Massachusetts, New Jersey, Oklahoma, Tennessee, Arizona and Arkansas, where she was first lady for more than a decade. She also won the caucuses in American Samoa.

Obama won Connecticut, Georgia, Alabama, Delaware, Utah and his home state of Illinois. He prevailed in caucuses in North Dakota, Minnesota, Kansas, Idaho, Alaska and Colorado. His Missouri victory was so close in the vote total that there was no telling whether he or Clinton would end up with a majority of the state's 72 delegates.

New Mexico shut its vote counting operation until 11 a.m. EST, the Democratic race too close to know the winner.

The allocation of delegates lagged the vote count by hours. That was particularly true for the Democrats, who divided theirs roughly in proportion to the popular vote.

Nine of the Republican contests were winner take all, and that was where McCain piled up his lead.

Alabama and Georgia gave Obama three straight Southern triumphs. Like last month's win in South Carolina, they were powered by black votes.

Democrats and Republicans alike said in exit polls that the economy was their most important issue. Democrats said the war in Iraq ranked second and health care third. Republican primary voters said immigration was second most important after the economy, followed by the war in Iraq.

The survey was conducted in 16 states by Edison Media Research and Mitofsky International for The Associated Press and television networks.

Source: Associated Press