"The Donald" would have his moment, they said. But by next February's primary, they had no doubt that it would be a distant memory.
There's legitimate intrigue surrounding Trump here as many Republicans are attracted to his straight-talking style and business savvy. But for now, said Andy Smith, who directs the survey center at the University of New Hampshire, "voters are essentially watching the show."
While Trump's announcement connected with voters here because of his bluntness and his populist message, "the key is to remember that voters are not locked into any of these guys," Smith said. "They may pay attention to him for a while and then move on. ... More than half will make up their minds in the final weekend of the campaign (seven months from now)."
The long game
With that in mind, candidates such as Bush, Carly Fiorina, Chris Christie, Rick Perry and Marco Rubio are playing the long game here.
It is not measured by the size of the crowds at events or standing in the polls, but rather by careful spadework -- voter by voter, town hall by town hall. And it is important to remember that perhaps no state loves a comeback quite like New Hampshire.
The formula is this: Maintain a comfortable position at the middle of the pack. Don't try to goose the poll numbers. Build relationships with voters with a tireless schedule and many visits like John McCain did in 2008 before he upended Mitt Romney's first bid for the presidency.
That means intimate -- but well-attended -- events such as Christie's recent gathering in the upstairs tap room at the Galley Hatch in Hampton. The space was packed so tight that the fire marshal stood guard at the stairs.
It requires taking questions at town hall events for more than an hour and lingering for handshakes as Bush has done on recent visits, and Rubio did Thursday in Exeter and later at an Elks Lodge in Salem.
And it demands careful cultivation of New Hampshire's influencers and politerati -- from business owners to county party chairs, not only with visits but with frequent telephone calls, like the ones Fiorina has been making since well before Christmas.
Take the example of Doug and Stella Scamman, who hosted Romney's campaign launch in 2011 at their 200 acre "Bittersweet Farm" in Stratham. They will hold the annual Seacoast Republican Women's Chili Fest in September.
Fiorina called the house Wednesday night (again) to chat, though Stella missed the call because she was out. Christie, who could announce his presidential bid this week, sat at the Scammans' dining room table chatting about politics and entitlement reform with the couple and a few interested friends for more than an hour between events earlier this month.
The New Jersey governor was so engaging in that setting that Stella Scamman said she was convinced New Hampshire voters would give him another look, despite his struggles over the past year in his home state.
"He has great strengths and points -- people will have to just listen and decide," she said.
But as she was explaining to a reporter in Exeter that Bush, Fiorina, Rubio and others were still very much in contention for her vote, a white van pulled up to the curb and Rubio popped out, greeting Scamman by her first name. It would be a long time, she said, before she could decide.
A window into Trump
There is no question that Trump has caught attention of voters here who are tired of the intransigence in Washington.
The opening of his headquarters in Manchester on Wednesday night brought out dozens of people, some of whom waited excitedly to take a photograph with his daughter Ivanka Trump.
The volunteer organizer who addressed the crowd before Ivanka's arrival, who lives across the border in Massachusetts, made the unusual comment that the New Hampshire event had drawn people from Chicago, Florida and New York, as well as her own state -- showing Trump's appeal, she said, across America.
Several voters in the crowd said they loved watching Trump on the reality show, "The Apprentice," and that it had given them a window into how he operates his businesses and hires "the crème de la crème," as one voter put it.
"He's down to earth and for the people," said Allie Trento, a 43-year-old nurse practitioner and Republican from Bedford, New Hampshire. "He doesn't have to do this."
Nancy Bigg, a retired real estate agent from Bedford, said she liked the fact "that he's cocky and forceful."
"People don't have confidence, the economy is not turning around," she said. "He could create jobs for people."
Bob Stanley, a retired police officer from Salem who ranked Trump and Rubio at the top of his list, liked Trump's announcement pitch that he has so much money that he can't be influenced.
"He's got $9 billion. Why is he getting into this other than he's worried about the country?" Stanley said. "He wants to take care of us."
'A guy who could sell me a car'
But Stanley said he was leaning more toward Rubio after listening to the Florida senator's question-and-answer session at an Elks Lodge in Salem on Thursday, attracted to what he perceived as Rubio's passion, charisma and authenticity.
"Marco Rubio, to me, is a guy who could sell me a car," Stanley said. "If he told me it was a good-running car, I'd believe him."
Other voters, including many who attended Rubio's events on Thursday, laughed when asked about Trump -- stating they could never imagine him as president.
"As great an individual as he is, I can't imagine it," said Michael DeWitt of Meredith, New Hampshire, who is on active duty in the Marines. "The things he's proposed. They're just not feasible."
With a tumultuous cycle ahead, Tom Rath, New Hampshire's former attorney general, noted that there is still hope or the candidates at the back of the pack.
Many may try to replicate "The McCain," but in a field this large, it may be a lot harder than they think, he said.
"You can't create the time, the moment," Rath said, "but you can get people to pay attention here. There's an attitude here. They like to keep a guy alive."