MANCHESTER, N.H. — Emboldened by Donald Trump's defeat in the Iowa caucuses, conservative leaders and rival candidates for the Republican presidential nomination began to challenge him aggressively in New Hampshire on Tuesday, aiming to cut into his wide lead here and perhaps even to embarrass him by denying him victory in a second consecutive state.
Sen. Ted Cruz of Texas, having prevailed in Iowa, teased Trump for having attacked him bitterly on the way to an embarrassing loss. Jeb Bush released a commercial in which he called Trump a man of "deep insecurity and weakness." Gov. Chris Christie sarcastically called him "Donald the Magnificent." And former Gov. John H. Sununu of New Hampshire, an elder statesman of the state Republican Party, branded Trump a "loser" with a string of business failures behind him.
For the first time, Republican leaders opposed to Trump's candidacy said they believed there was a chance to break his grip on New Hampshire as the party establishment closes ranks around a smaller number of candidates and Trump faces new threats on the right.
On the Democratic side, too, the nomination fight quickly descended on New Hampshire. Hillary Clinton, who won in Iowa by the narrowest of margins over Sen. Bernie Sanders, declared in Nashua that she would battle the Vermont senator in a "contest of ideas" here leading up to the primary on Tuesday.
The state has been receptive to Clinton in the past, and revived her candidacy in the 2008 primary after her defeat in Iowa by Barack Obama.
But Sanders has held a solid advantage in the New Hampshire polls, and his campaign has projected confidence about its prospects. He told reporters that his performance in Iowa was a show of strength against Clinton's powerful political operation, and vowed to stay in the race until the Democratic convention in the summer.
It was the Republican race, however, that appeared more unsettled on Tuesday. Trump has towered over the Republican presidential race for months, but the campaign here took on a distinctly new tenor and urgency in the aftermath of Iowa.
For Cruz and Sen. Marco Rubio of Florida, the third-place finisher in Iowa, the caucus results were a pretext to argue, more forcefully than ever, that it was time for the party to pick them instead of Trump.
Both senators hope to extend their momentum in New Hampshire, with Cruz looking to peel away Trump's supporters on the hard right and Rubio working to consolidate votes from more mainstream Republicans and independent voters.
Trump, meanwhile, was uncharacteristically silent for much of the morning — until he began to grumble, on Twitter, that he had been denied due credit for a silver medalist's performance in the caucuses. Late in the afternoon, Trump's campaign announced he had won the endorsement of Scott P. Brown, the former Massachusetts senator now living in New Hampshire.
At a campaign stop in Milford, New Hampshire — his first public appearance since Monday's defeat — Trump told reporters he expected to keep his lead in the state. "I think we will finish first," he said. "I would like to finish first."
The extent of Trump's vulnerability in New Hampshire is still a question mark. He has long led the polls here by wide margins, and even as he conceded defeat in Iowa, Trump bragged that he was ahead in New Hampshire by 28 points. (It was unclear what poll he was citing.)
The determination to take on Trump transcends the different political camps on the Republican side in New Hampshire. Gordon Humphrey, a former senator and a longtime conservative activist here, said frustrated Republicans finally had a chance to thwart Trump's campaign, "thanks to the people of Iowa."
Humphrey, who is supporting Gov. John Kasich of Ohio, said Cruz would probably draw the most support directly away from Trump. But in the process, he said, Trump could become more susceptible to a challenge from the more traditional Republican candidates.
"Trump has been looking good mainly because the sane vote has been so broken up, so fractured," Humphrey said. "Now, less so."
For three candidates who fared poorly in Iowa — Christie, Bush and Kasich — the New Hampshire campaign has become a fight for survival. Long eclipsed by Trump, they now must also contend with Rubio's status as the only candidate outside the hard right to perform well in the caucuses.
Kasich acknowledged at a stop in Claremont on Tuesday that he could not afford a lopsided loss in the state. "If I get smoked in New Hampshire," he said, "I'm going home." And on Monday evening, Christie set a kind of bar for his own performance, telling voters in Hopkinton he expected New Hampshire to narrow the field to just four or five candidates.
Among Democrats, there is no expectation that the New Hampshire primary will be conclusive in the race. Clinton and Sanders are the only two candidates left, after former Gov. Martin O'Malley of Maryland withdrew on Monday night. Both have access to tens of millions of dollars in campaign funds, and they have amassed national networks of supporters who are unlikely to desert them.
But each appears determined to make an important symbolic point in New Hampshire. For Sanders, it is his best opportunity to win an early primary outright and to gain more traction nationally as the race heads to larger, more urban and diverse states, where Clinton is seen as holding an upper hand.
And Clinton on Tuesday appeared determined to deepen the contrast between herself, as a candidate of liberal beliefs but pragmatic instincts, and Sanders' more rigidly ideological message. In an MSNBC interview broadcast Tuesday night, she said the country had to "get back to the big center," politically. "We've got to get back to solving problems," she said.
No Republican is likely to get such a clean shot at making the empty-promises case against Trump in New Hampshire.
Over the last few weeks, the race here has erupted in extravagant hostilities among them, as the candidates and their supporters have delivered increasingly venomous attacks in speeches and paid advertisements.
Even as these candidates took on Trump with renewed vigor Tuesday, they also redoubled their attacks on each other. Christie referred to Rubio in acid terms at a morning event, describing him as "the boy in the bubble" who had never faced a truly taxing political test.
The evening before, perhaps anticipating the outcome of the caucuses, Bush derided both Rubio and Cruz as legislative "back-benchers, who have never done anything of consequence in their lives."
Though Trump may yet prevail in New Hampshire, there was a palpable sense of relief among Republican leaders in the state and nationally, as the prospect of a Trump sweep in the early primary states evaporated.
Should he have won in both Iowa and New Hampshire, it would have been difficult to slow his advance in the race without a painful, monthslong nomination fight against the most overtly ruthless candidate in recent memory.
Shannon McGinley, a leading conservative activist in New Hampshire, said the Iowa outcome had buoyed Trump's detractors here.
"For a lot of folks who are really upset about the idea of having Trump as our nominee, it gives us hope in America — not as crazy and lost as we thought it might be," said McGinley, who added that she decided this weekend to support Rubio.