KEENE, N.H. — The Democrats running for president blasted into New Hampshire Tuesday ready for the new realities of the Democratic contest: Hillary Clinton dug in for a longer-than-expected nomination slog, while Bernie Sanders tried to seize momentum from his near upset in Iowa.

The candidates came off a history-making night in Iowa with what the state party described early Tuesday morning as the closest Democratic caucus ever. In the final tally, a mere 0.3 percent separated Clinton from Sanders. As of Tuesday evening, Sanders had yet to concede the Iowa race and still wanted to “look’’ at close precincts in which the winner was determined by a coin toss.

The photo finish was close enough to infuse Sanders’ populist campaign with the credibility to keep fighting in New Hampshire and beyond.

“I continue to believe she’s going to be the nominee,’’ said Gus Bickford, a Massachusetts super delegate who’s committed to Clinton. “But it’s going to take a little longer.’’

Since Sanders has almost no support from the Democratic establishment he must run a nearly perfect campaign on his own to remain viable, and he must continue to generate enthusiasm among the hundreds of thousands of supporters, mostly outside of the political world, who are fueling his candidacy.

So far, he’s doing it: His campaign reported that it received $1 million in donations in the 90 minutes after Sanders spoke about the results in Iowa, calling the race a virtual tie.

Clinton had for months been seen as the likely winner in ­Iowa. Now expectations flip, with Sanders the one who is supposed to do well in New Hampshire. It’s a place that neighbors his home state of Vermont, and he’s been polling ahead of Clinton here for months.

“Both campaigns leave Iowa having survived,’’ said Anita Dunn, a Democratic strategist who is not working for either campaign. “That’s the most realistic sense of where we are.’’

Clinton arrived here Tuesday in seemingly buoyant spirits. But she also faced the perception that her near loss in Iowa­ reinforced persistent questions about whether she can generate enough enthusiasm, particularly among young voters or those new to the political process.

She quickly got back to work on the stump, greeting voters in a packed gymnasium at Nashua Community College.

“I am so thrilled that I come to New Hampshire after winning Iowa,’’ Clinton said to the crowd. “I have won and I have lost there, and it’s a lot better to win. We’re bringing all that energy, all that excitement, all that determination right to New Hampshire.’’

There were times when Clinton’s words were barely audible above the shouts of support from voters, many of them wearing the bright blue campaign stickers they had received upon arrival.

Although the campaign had recently taken on a more negative tone, Clinton took pains to be respectful of Sanders — referring to him as her “esteemed opponent.’’

History shows that New Hampshire can be good to Clinton: She limped into the state in 2008 after a devastating third- place finish in Iowa. Over the next few days, she overcame a double-digit deficit in the polls and emerged the victor over Barack Obama by dint of hard work and a few lucky breaks.

In 2008, Clinton benefited from, among other things, Obama’s gaffe during a debate held days prior to the primary at which he said Clinton was “likable enough.’’ That put her in a defensive crouch, causing an outpouring of sympathy for her, particularly among women.

Team Clinton 2016 is pushing to add another debate to the schedule on Thursday night in New Hampshire. It’s a shift; she’d previously said she was OK with the abbreviated debate schedule on the Democratic side.

Sanders hadn’t agreed to do it as of Tuesday evening, and he was trying to push for additional debates in Michigan, California, and New York.

The Vermont Senator employs several former Obama strategists and is well aware of Clinton’s political history in the state, noting how she won here in 2008. “Secretary Clinton has a very formidable political organization,’’ Sanders assured reporters.

He was greeted by fans chanting “feel the Bern’’ in Keene, a cozy town nestled among mountain streams and thick forests. Both levels of a downtown theater were packed with supporters, and he stressed that he’s in the race for the long haul.

“In Iowa we took on the most powerful political organization in this country,’’ Sanders said to the crowd. “We began the political revolution, not just in Iowa, not just in New Hampshire, but all over this county.’’

He doubled down on his core message that America needs sweeping change in its politics. “This campaign is about us urging the American people to think big,’’ he said to a cheering crowd. “Not to take for granted what we see every day.’’

Sanders and his wife, Jane Sanders, flew on a charter plane from Des Moines to Manchester. The Clinton campaign did the same for top aides and reporters, though the Clintons flew on a separate plane.

Aboard Air Sanders, Jane Sanders told reporters that watching the results come in Monday in Iowa was “like a roller coaster.’’ She called the final tally “humbling.’’

“We have a great relationship with Vermonters,’’ she said. “We didn’t expect to have that with Iowans so quickly.’’

Clinton also had a late night and was accompanied on the trail by her spouse. “Well, we’re here, and we’re awake,’’ President Bill Clinton said in his signature raspy voice while introducing his wife in New Hampshire.

Annie Linskey can be reached at annie.linsky@globe.com. Akilah Johnson can be reached at akilah.johnson@globe.com.