The 2016 Republican primary has turned into a puzzle about how to deal with Donald Trump.

The new dynamic has come into focus this week as Trump’s opponents debut strategies for engaging the white-hot front-runner whom they believe, and in some cases fear, could be a dominant force for some time to come.

Though flummoxed by Trump’s staying power and aghast at the coarse tone he has brought to the race, party elites said they have no plan to take him down. Donors feel powerless. Republican officials have little leverage. Candidates are skittish. Super PAC operatives say attack ads against him could backfire. And everyone agrees that the Trump factor in this chaotic multi-candidate field is so unpredictable that any move carries dangerous risks.

The non-Trump candidates are falling into three categories: Those who are emulating and befriending him in an effort to win over his supporters; those who are assailing his background or calling him out for his views and rhetoric; and those who prefer to stay silent, as if hunkering down in the basement to ride out the tornado.

“No one has figured out how to handle Trump,” said former New Jersey governor Thomas H. Kean Sr. (R). “Everyone underestimated him terribly from Day One. But as someone who knows him and knew his father — the whole family — I can assure you, that was a mistake.”

Jeb Bush’s latest tack illustrates the tension. The former Florida governor launched a tough verbal assault against Trump this week in New Hampshire, saying he is not “a proven conservative” and ticking through his past liberal positions. Yet Bush’s allied super PAC vowed not to spend money to supplement the candidate’s barbs.

“If other campaigns wish that we’re going to uncork money on Donald Trump, they’ll be disappointed,” said Mike Murphy, chief strategist of the Right to Rise PAC. “Trump is, frankly, other people’s problem. We’d be happy to have a two-way race with Trump in the end, and we have every confidence that Governor Bush would beat him.”

Lesser-funded candidates have been eager to see a big-spending push to go negative on Trump — and hoping Right to Rise might lead the way — because the billionaire businessman has been suffocating them for weeks with his saturation media coverage.

Murphy said the super PAC would concentrate instead on “telling the Jeb story,” an effort begun Thursday with pro-Bush fliers mailed to more than 200,000 homes in New Hampshire and Iowa and continuing next month with television ads.

Former Texas governor Rick Perry was one of the first candidates to aggressively take on Trump, calling him “a cancer on conservatism.” Yet he slipped further behind in the polls and can no longer afford to pay his staff. Some allies are pressuring the pro-Perry super PAC, Opportunity and Freedom PAC, to spend the millions of dollars it has stockpiled against Trump.

“Right now, we are solely focused on supporting Governor Perry in the early states,” said Austin Barbour, the super PAC’s senior adviser. About Trump, he said, “we’ll cross that bridge when we get there.”

One reason outside groups are reluctant to launch an ad war against Trump is that research has convinced some that he is not an ominous threat to the GOP brand.

The audience stands and waves in support of Donald Trump in a crowded auditorium at a town hall meeting in Derry, N.H., on Wednesday. (Melina Mara/The Washington Post)

At a recent focus group of Hispanic voters in Denver conducted by a conservative organization, which requested anonymity because of client agreements, several voters said they see Trump more as an entertainment figure than a representative of the Republican Party, according to an attendee. That could change, however, as Trump’s campaign continues and some candidates move to embrace his positions.

One party eminence who has been relatively silent is Mitt Romney, the 2012 nominee who flirted with but ruled out another run in January. A potentially powerful voice in countering Trump, he has resisted weighing in at length, though friends said he has been monitoring the summer maneuvering with interest. He declined an interview request.

Corey Lewandowski, Trump’s campaign manger, said he was struck by the influence that Trump’s immigration plan, released Sunday, has had on the race. “It’s clear Mr. Trump has set the agenda for this race and will continue to,” he said Thursday.

As the GOP has grown increasingly uncomfortable with Trump as its presidential poll-leader, the vitriolic remarks about him have increased. On Thursday in Keene, N.H., Bush repeated charges against Trump that he first leveled Wednesday night when the two men held dueling town hall meetings.

“He’s been a Democrat longer than being a Republican,” Bush said, reminding people that Trump once supported tax increases, abortion rights and a single-payer health-care system.

Yet Bush also defended his use of a controversial phrase used by Trump: “anchor babies,” a reference to U.S.-born children of undocumented immigrants that many Hispanics consider offensive. “Do you have a better term?” Bush snapped at a reporter in Keene.

Democrats reacted with glee, saying Bush had committed a gaffe that would haunt him in the general election with Latino voters should he become the nominee. Front-runner Hillary Rodham Clinton and her campaign disseminated Bush’s “anchor babies” comment across social media and in text messages to supporters.

If Bush was using a butter knife against Trump, Rand Paul has taken out a machete. The senator from Kentucky, who tangled with Trump at the Aug. 6 debate, labeled him a “chameleon” and accused him of exploiting the tea party. His campaign released a video mashing up old TV clips of Trump sounding like a liberal.

Privately, Paul repeatedly mocks Trump, and he has marveled at how easily baited the reality television star has been, according to associates.

Paul and Sen. Ted Cruz (Tex.), who are running insurgent campaigns, are seen as having the most to lose from Trump. But the two senators have taken opposite approaches to him.

Cruz, positioning himself to inherit Trump’s support should the front-runner collapse, has hectored the media for their interest in his possible breaks with Trump and endorsed Trump’s call to end “birthright citizenship” for the children of undocumented immigrants.

Cruz also has cultivated a chummy relationship with the developer. During a meeting at Trump Tower in New York last month, Cruz invited Trump to visit the U.S.-Mexico border. “Be my guest, and we’ll go together,” he told Trump, according to Cruz spokesman Rick Tyler.

An additional presence in the be-like-Trump camp is Wisconsin Gov. Scott Walker, who has fallen behind Trump in must-win Iowa and nationally and is lunging to the right to win back grass-roots activists.

Trying to channel Trump’s anti-establishment anger, Walker spiced up his talking points on the stump this week and embraced Trump’s immigration plan by saying that he also wants to build a wall along the southern border and would support ending birthright citizenship.

Other contenders, such as Sen. Marco Rubio (Fla.), are treading carefully to stay out of Trump’s cross-hairs. When Trump hinted Wednesday that Rubio might be looking to go after him, Rubio strategist Todd Harris took to Twitter to insist that the campaign would not run attack ads.

Rubio instead is sticking studiously to his positive generational message, even though he is being drowned out. Asked about Trump’s rise in Detroit on Thursday, Rubio said Republicans can “use this anger to motivate us. But we cannot let it define us.” Then, he added, “This is a great country,” a subtle counter to Trump’s “Make America Great Again” slogan.

Ohio Gov. John Kasich has taken a similar approach, along with New Jersey Gov. Chris Christie, who has avoided clashes with a man he considers a “friend.”

“They’ve had a long-term personal relationship,” Christie adviser Mike DuHaime said. “Governor Christie is out there articulating why he’s prepared to be president, and he has done so in a respectful manner.”

Christie did come out sharply against Trump’s immigration plan and said “it doesn’t make any sense,” something DuHaime pointed to as an example of Christie’s gubernatorial gravitas.

Some of Christie’s donors have encouraged him to take a more combative line against Trump. “What donors who support the real candidates can do is to push their candidates to stand up to him and say, ‘Enough is enough and this is not acceptable,’ ” said one donor who spoke on the condition of anonymity.

Doug Gross, a top Republican in Iowa, said, “It’s the ones who won’t win anyway, I suppose, who can take the gloves off. Those who have a chance of winning don’t want to engage with a megalomaniac with a billion dollars.”

David Weigel, Katie Zezima, Jenna Johnson and Sean Sullivan in Washington and Ed O’Keefe in Keene, N.H., contributed to this report.