Businessman and Republican candidate for president Donald Trump greets supporters after speaking at a campaign event in Laconia, N.H. (Dominick Reuter/Reuters)

Democratic presidential front-runner Hillary Rodham Clinton spent 15 minutes here Thursday calmly unveiling a corporate profit-sharing plan as part of her proposal to grow middle class incomes and rein in the power of Wall Street banks.

Later in the afternoon, about an hour’s drive up State Highway 11, Donald Trump held a rowdy campaign rally where he lashed out at opponents in both parties and stressed his controversial immigration positions. There were no concrete policy ideas.

The contrast highlighted a development that thrills Democratic operatives even as it unsettles their Republican counterparts: Trump, long seen as a political sideshow, is surging in the polls — offering Clinton a plum chance to boost her preferred image as a serious, seasoned alternative to a chaotic field of Republican presidential hopefuls now headlined by the brash billionaire.

“The juxtaposition of the two — your head may explode,” said Kathy Sullivan, a former New Hampshire Democratic Party chair, who is backing Clinton.

Holding her first town hall meeting of the campaign, Clinton made a detailed pitch for her plan to spur more companies to share their profits with employees by offering a two-year tax credit as an incentive. The credit would be equal to at least 15 percent of profit sharing distributions and the profit sharing would be capped at 10 percent on top of current employee wages.

“Everybody running on the other side has a different economic philosophy,” Clinton said at the town hall, which came the same week she gave a speech laying out her economic message. “They really still believe if you cut taxes on the wealthy, if you lift regulations on corporations, that somehow economic activity will trickle down to all the rest of us.”

Trump’s explosion onto the Republican campaign has complicated the Republican effort to counterpunch. It’s hard to get people to focus on middle class pocketbook issues when the ­headline-grabbing mogul is on the trail boasting of his vast wealth, offending neighboring nations and tangling with critics in both parties.

In a sweltering room in Laconia, Trump took swipes at a laundry list of foes, from Clinton and President Obama to GOP rival Jeb Bush, as supporters cheered him on. He stood by his recent remarks that illegal immigrants from Mexico are “rapists” who are bringing “drugs” and “crime” into the country.

“It turns out I was right,” Trump said, citing an illegal immigrant who allegedly killed a woman in California, and a Mexican drug kingpin who escaped from prison.

Later in his remarks, Trump summed up his candidacy: “The American dream is dead, but I’m going to make it bigger and better and stronger than ever before.”

While Trump’s Republican primary opponents were initially slow to critique him, some have recently become more forceful.

“I have a message for my fellow Republicans and the independents who will be voting in the primary process: what Mr. Trump is offering is not conservatism, it is Trump-ism – a toxic mix of demagoguery and nonsense,” said former Texas governor Rick Perry (R) in a Thursday statement.

After making headlines with controversial remarks about immigrants, 2016 Republican presidential candidate Donald Trump is seeing a surge in the polls. A new Washington Post-ABC News poll finds his favorability increased among Republicans — but is it too early to read into the numbers? (Julie Percha/The Washington Post)

Still, Sen. Ted Cruz (R-Tex.), who huddled with Trump on Wednesday, has praised his blunt tone. Other presidential contenders have shown reluctance to openly bash him.

“Donald Trump can speak for himself, and I’m not going to put words in the mouth of any candidate, him or anybody else out there,” said Wisconsin Gov. Scott Walker (R), who also campaigned in New Hampshire on Thursday.

Trump, who has flirted with running for president in past elections, is diving deeper into the race with each passing day. He has launched an full-fledged campaign, hired early state staff and on Wednesday said he filed a financial disclosure with the Federal Election Commission, though he did not release a copy of that disclosure.

National polls show him to be a top-tier candidate. But many Republicans remain unconvinced he is committed for the long haul.

“I don’t think he is looking at all like serious candidate,” said former New Hampshire Republican Party chairman Fergus Cullen. “There are some trappings of a serious campaign, but this is a Potemkin effort at best.”

His effort may not be built for the long haul — his campaign’s burn rate, a comparison of money raised with money spent, was an astounding 74 percent, highest in the Republican field. But some Republicans worry that even a primary season Trump candidacy may cost them next year, as a new Univision News Poll shows that 70 percent of Hispanic voters say they have an unfavorable impression of him.

The Clinton-Trump roadshow isn’t over yet: Trump is the feature speaker at a Republican dinner on Friday in Arkansas, where Clinton — whose husband, Bill Clinton, was the state’s governor — will speak Saturday at a Democratic dinner.

Jose DelReal contributed to this report.