WASHINGTON John McCain dug in for a long night that could bring him close to the Republican presidential nomination Tuesday, challenged by Mitt Romney, who campaigned as if conservatism itself were on the line. Calmer, but with stakes also sky high, Barack Obama and Hillary Rodham Clinton predicted this day of decision would only keep their rivalry alive.
Voters participated in nearly two dozen contests coast to coast, some in weather as stormy as the presidential competition itself. Super Tuesday offered a treasure chest of delegates, although not enough to clinch a nomination.
In West Virginia, Mike Huckabee prevailed in the state's GOP nominating convention to take the first prize of the day 18 delegates. The former Arkansas governor, distant in national polling, won a convention majority when McCain's supporters threw their votes behind him. Romney flew through the night from California to address the convention, but fell short.
Tempers heated up between the top GOP hopefuls, with McCain attacking his opponent for having a "terrible record as governor" and Romney retorting that he must be in strong contention if he's so able to get under the Arizona senator's skin.
And in West Virginia, Romney told supporters that McCain's support for global warming curbs "would effectively kill coal," a lifeblood of the state, and just one of the McCain positions he branded out of the conservative mainstream.
McCain rallied in Manhattan before flying to California, the state offering the richest delegate prize Tuesday. Nationally, opinion polls suggested McCain had built an advantage over the former Massachusetts governor.
"I have the judgment and the experience to lead this nation in the transcendental challenge of the 21st century, and that's the struggle against radical Islamic terrorism," McCain told a New York rally, entering to the theme from "Rocky" and an introduction from former rival Rudy Giuliani.
The tightness of the Democratic race and the sheer scale of the voting in nearly two dozen states left the candidates wary of making predictions as they offered last minute pitches.
"We're all kind of guessing about what it's all going to mean because it's never happened before," Clinton said. The New York senator said she found it all "intriguing and somewhat mystifying."
Obama said a "split decision" was likely. "I don't think today's going to end up being decisive," the Illinois senator said.
Many voters seemed split, too, and late to make up their minds.
Linda Ster, a 44-year-old Nashville social worker, juggled Clinton's experience with Obama's vision of change and decided Monday night she favored the latter and not another Clinton in the White House.
"I don't just want change, I want radical change," she said. "I have voted for a Clinton already. I want something different way different this time."
In Buffalo, N.Y., Paul Dissek, 63, waited alone in the fog outside a library for the polling station to open. A year after retiring from Bethlehem Steel, he lost his health coverage and pays for it himself now. His choice: Clinton, who proposes to make health insurance mandatory.
"I lost my health insurance with the steel plant," he said. "I figure she'd be the one to get it."
A frigid rain fell in parts of the Northeast, part of a wintry mess expected in the region, and voters braced for snow in a large corridor from southwest Kansas to northern Michigan. A winter onslaught was forecast in Illinois later in the day.
In Topsfield, Mass., where a steady stream of voters filed to a polling place in a cold rain, Mary Jordan, 43, a teacher's aide, said she didn't make her decision until she was in the polling booth. Voting Republican, she went for Romney, the state's former governor, because of his business experience, while offering no one a glowing endorsement. "I think he's the least unlikable," she said. "I really didn't like any of them."
The Iraq war was central to Kieth Anderson, 34, when he voted for Obama at a Phoenix church. He's lost friends in the war and wants others still serving to come home.
"I'm certain my friends will be back in a year if he's elected."
Romney sought until the end to exploit the right's mistrust of McCain, who opposed President Bush's tax cuts when they were introduced, departed from orthodoxy on immigration, favors mandates to slow global warming and led campaign finance reforms that activists say trampled on their speech rights.
Huckabee focused on the South, his continued candidacy an open question as was Romney's viability if he couldn't pull off surprises Tuesday.
McCain and Romney also clashed from afar over a letter that Bob Dole the former senator and decorated World War II veteran wrote in support of McCain. "Well, it's probably the last person I would have wanted to have write a letter for me," Romney said on Fox News, likening McCain's candidacy to Dole's losing 1996 presidential bid. McCain called on his rival to apologize. "This is no way to end up this campaign," McCain said, "by attacking a genuine American war hero."
Romney told reporters he meant no such offense. "I think very highly of Senator Dole," he said, "but I do not think highly of the mental set that says we should choose our nominee based on how many years they've served and how long they've waited in line."
Clinton voted near her home in Chappaqua, N.Y., accompanied by husband Bill and daughter Chelsea. "You're a Democrat, right?" election worker Evan Norris joked. "True blue" she responded, laughing. She said of Super Tuesday: "The stakes are huge."
In Illinois, Obama supporters expressed pride for the home-state senator as they voted. "We have something great to vote for today," said Catherine Braendel, 44, a marketing consultant who lives down the street from Obama in Chicago.
Heather Holliday, 28, a Chicago sales executive, credited McCain with wisdom earned as a prisoner of war in Vietnam and as a lawmaker who looks at both sides of an issue. She voted for him.
"He understands war better than the others," she said. "He's been through hell and back." McCain "understands what it is not to be safe."
Her comments spoke to McCain's appeal to Republican moderates and independent voters. But he's struggled to close the sale with his party's base after coming strikingly far without its solid support. "I will preserve my proud conservative Republican credentials" while extending a practiced hand to Democrats, he promised.
After months when it was all about expectations and momentum, not to mention confusion, real numbers finally became important.
The two dozen contests Tuesday were delivering 1,023 Republican and 1,681 Democratic delegates. The number needed to win the nomination: 1,191 Republican and 2,025 Democratic.
John Edwards' departure after South Carolina's primary simplified the math but little else on the Democratic side.
Since winning that state, Obama has collected a succession of marquee endorsements several of them named Kennedy and pulled into a statistical tie with Clinton in a national poll and in California, Tuesday's biggest prize with 370 Democratic delegates.
The two were campaigning for history as well Clinton seeking to become the first female president, Obama the first black one.
Little separates them on most issues, including universal health coverage, ending U.S. military involvement in Iraq and raising taxes on the rich. And neither has accounted fully for all their proposed spending.
Party rules were stacked against a Tuesday knockout for Democrats. All their primaries and caucuses were awarding delegates proportionately, so coming in second counted. In the Republican field, nine contests offered all delegates to the winner.
Associated Press writers Teresa M. Walker, Carolyn Thompson, Don Babwin, Dave Carpenter, Ashley M. Heher Jim Fitzgerald, Beth Fouhy, Glen Johnson, Jim Kuhnhenn, Nedra Pickler, Libby Quaid and Liz Sidoti contributed to this report.