A flag hangs at the Chez Vachon restaurant in Manchester, N.H., a popular spot for politicians where Hillary Clinton greeted voters Monday. (Melina Mara/The Washington Post)

With a snowstorm bearing down, presidential candidates scurried across New Hampshire on Monday, ­leveling inflammatory attacks against one another while pleading with voters for their support in Tuesday’s primary election, which appeared likely to settle little in the wild nominating contests.

Donald Trump held a sizable lead in the Republican race and appeared poised to win his first contest of the 2016 campaign after finishing second in Iowa a week ago. But behind the New York businessman, five other candidates waged a fierce battle for coveted top-tier finishes and the bragging rights and resources that could come with them when the campaign heads next to South Carolina.

In the Democratic race, Sen. Bernie Sanders maintained his double-digit lead over former secretary of state Hillary Clinton. After winning only narrowly in Iowa, Clinton, the once-presumptive nominee, was bracing for defeat here and hoping to keep the damage from spilling over into upcoming states where she long has been dominant.

Sanders is capitalizing in part on the fact that he represents a neighboring state, Vermont, though his campaign has been fueled more by widespread discontent with the political system among many liberals and the enthusiasm of young voters for the promise of a “political revolution.”

In diners, on factory floors and at big rallies, the candidates encountered voters, one after another, who had yet to make up their minds — a reminder that New Hampshire is a state where voters have sprung surprises in the closing days of past presidential primaries.

Despite the fact that neither contest this year appears to have a genuine race for first place, the net effect of the voting could be to draw out both nomination battles well into the spring. A commanding upset by Sanders that further exposes weaknesses in Clinton’s coalition, along with a photo finish for second and third place in the GOP race, could upend both contests.

For Republicans, the campaign trail Monday was like a game of political billiards, with attacks flying fast and in all directions, reflecting the jumbled field and the uncertain fates that await so many of the candidates. Jeb Bush fired at Trump, Ted Cruz, John Kasich and Marco Rubio. Chris Christie savaged Rubio, and Rubio smacked back. And Trump slammed Bush and Cruz.

Kicking off the day at a town hall meeting in Salem, Trump accused Cruz, the senator from Texas and winner of the Iowa caucuses, of being “politically correct” and “very queasy” on the issue of interrogation of terrorism suspects. Then he cut into Bush, calling him a “stiff” and accusing him of acting like a “spoiled child.”

“You have to go out and vote tomorrow,” Trump said. “You have to do it, because, you know, we have to get rid of the Bushes of the world. You know, guys like that will never straighten out this country.”

Reaching for the jugular, Trump said on CNN that Bush “has to bring his mother out and lug his mother around at 90 years old. I think it’s a very sad situation.”

Bush offered a Trump-style ­retort on the mogul’s preferred mode of communication, tweeting at him, “you aren’t just a loser, you are a liar and a whiner.”

The Democratic side was hardly harmonious as Clinton sharpened her knife to bloody Sanders. He has attacked Clinton repeatedly for her long ties to Wall Street and her acceptance of campaign contributions and personal speaking fees from major financial firms.

On Monday, Clinton tried to turn the tables, portraying Sanders as hypocritical because he had accepted “about $200,000” from Wall Street firms through the Democratic Senatorial Campaign Committee. Sanders campaign manager Jeff Weaver called that suggestion “false” and “beyond preposterous.”

Clinton’s husband, Bill, effectively hurled the kitchen sink at Sanders in a speech Sunday, accusing Sanders’s followers of sexism and his campaign of fabricated attacks. But the former president showed considerable restraint Monday and described his weekend outburst as the emotions of a worried spouse.

“The hotter this election gets, the more I wish I was just a former president and, just for a few months, not the spouse of the next one,” he said. “I have to be careful what I say.”

At day’s end, however, Clinton said as he introduced his wife in Hudson, “Finally, the dam broke in the polarization of the campaign, and we are finally free” to have a discussion of whose ideas are better.

The Clinton family made an all-out push to secure votes in New Hampshire, a state that has fueled comebacks for both Bill and Hillary in past campaigns.

“It’s going to be a race to the finish,” Hillary Clinton said.

But the race seemed to be Sanders’s to lose. At his stops Monday, he did not directly criticize his opponent, instead restating his broad assault on the corrupting influence of money in politics and the power and wealth of Wall Street and corporate America.

“We are running a very radical campaign because we are telling the American people the truth,” Sanders said at a midday rally in downtown Manchester.

For the Republicans, the character of the race appeared to change over the weekend after a debate in which Rubio faltered in the face of blistering attacks from Christie. The senator from Florida appeared to have gained some momentum from his strong third-place finish in Iowa, but the question was whether his debate foible set him back and how much of an opening it gave Christie, as well as Ohio Gov. Kasich and former Florida governor Bush.

Rubio sought to stoke positive energy as he stopped by his ­campaign headquarters in Manchester to give a pep talk to volunteers. Walking into the office to chants of “Marco! Marco!,” the senator said his campaign here was “closing really strong.” He noted that supporters had descended on New Hampshire from far and wide. “It’s huuuge,” he said, doing his best Trump impersonation.

He also played up his believed strength in a general election: “Who gives us the best chance to win? I know that I do. I know that we do. And you know who else knows that? Hillary Clinton.”

Cruz, who spent the end of his Iowa campaign in a rhetorical splatter-fight with Trump, closed out his New Hampshire tour with only sparing mention of his rivals.

But he appeared to be laying the groundwork for a debate over women in the armed forces that he might push more aggressively once the campaign moves to South Carolina, which has a large military presence and holds its GOP primary Feb. 20. On Monday in Barrington, Cruz insisted that Republicans who refused to rule out a military draft for women — as some of his opponents have — were “nuts.”

New Hampshire polls have shown Cruz, Rubio, Kasich and Bush in a jumble for second place behind Trump, with Christie, the New Jersey governor, lagging in sixth place.

Cruz, Trump and Rubio established their longevity with their Iowa placements, but the New Hampshire primary threatens to knock one or more of the governors out of the race. Even as they all vowed to carry their campaigns onward regardless of Tuesday’s results, the sense of urgency was evident all day.

Christie began the morning by dropping to one knee, all but begging a woman who claimed to be undecided to cast her ballot for him. After he gave her a lengthy answer about Social Security reform, she said he had her vote. She was one of two women who publicly declared their allegiance after arriving to the event unsure.

The three governors drew plaudits for their performances at Saturday’s debate, but each recognized the precariousness of their candidacies and the importance of finishing ahead of one another.

Though Bush’s campaign has languished for months, he began to find his voice in the closing week in New Hampshire, which he hoped would spark a revival.

Kasich took a different tack from the other Republicans, continuing with his positive theme and his call to bring Republicans and Democrats together. “You have to unite people,” he said at a town hall in Plaistow. “You have to have some people in the other party. You’re an American. You’re not a Democrat or Republican.”

Kasich bemoaned America’s reputation around the world, saying that foreigners “look at these goofballs across the ocean. We’ve got to get our act together.”

Jose A. DelReal in Portsmouth, Anne Gearan in Rochester, Jenna Johnson in Salem, Michael Kranish in Plaistow, Abby Phillip and Sean Sullivan in Manchester, David Weigel in Barrington, and Ed O’Keefe in Nashua contributed to this report.