AFP Action, a political advocacy group backed by conservative billionaire Charles Koch, is sending up to 100 additional employees to knock on doors in the final sprint ahead of Tuesday's vote. SFA, another deep-pocketed PAC supporting Haley, released a new ad this week featuring New Hampshire residents calling Trump a bully and a liar.

And Haley, who served as United Nations ambassador under Trump, has reworked her stump speech after her third-place finish in Iowa to go harder after the former president, though she still avoids some topics, like Trump's attempts to overturn his 2020 election loss to President Joe Biden.

At a packed event center in Hollis, New Hampshire, on Thursday, she took a dig at Trump's age, described him as an irresponsible spender and accused him of being "vindictive" and "too focused on investigations to keep us from going to war."

The all-out effort is a sign of the stakes for Haley: She is under intense pressure to win the second contest of the Republican primary race or risk closing her already-narrow path to the nomination.

Three major donors told Reuters they feared funding for her campaign will dry up if she comes up short in New Hampshire, where polling averages show she trails Trump by about 14 percentage points. Trump trounced Haley and Republican Governor Ron DeSantis in Monday's Iowa causes.

"If Trump wins the first two states, it's hard to see how he's not the nominee," said Alex Conant, a veteran Republican operative. "I'm sure Haley will claim success if she is a very close second, but where does she go from there?"

New Hampshire has a high concentration of white-collar, college-educated professionals, a demographic group that is notably cool on Trump. The state also holds a semi-open primary allowing voters unaffiliated with either party to cast a ballot, many of whom are centrist leaning.

"Where Donald Trump under-performs is in white-collar suburbs," said Greg Moore, an AFP regional director. "And New Hampshire is loaded with them."

Moore said AFP Action had swelled its ranks in the state in recent weeks from seven paid employees to 60 and would now bring in up to 100 more workers from other parts of the country to encourage Haley supporters to go to the polls or persuade those on the fence.

The scripts that door knockers typically use, provided to Reuters, argue that Haley would have a better chance than Trump of beating Biden in November.

Haley and her outside super PACs are also leaning hard on New Hampshire's Republican Governor Chris Sununu, who endorsed Haley in December and is among the country's most popular governors.

In Haley's campaign swing through New Hampshire this week, the two stuck together like glue, with the governor typically warming up the crowd and then speaking to reporters, a function Haley herself has largely eschewed.

'BINARY CHOICE'

Haley has begun framing the primary race as a two-person battle between her and Trump, with DeSantis trailing in a distant third at 5% in New Hampshire.

In the upscale suburb of Hollis, Haley, the daughter of two immigrants from India, presented herself as a "new generational conservative leader" who is less divisive than both Trump and Biden.

She took brief swipes at the age of both men - Trump is 77, Biden is 81 and Haley turns 52 on Monday - and said she was more electable than Trump in a general election.

"When you think of more of the same, more of the same is the fact that over 70% of Americans don't want a Trump-Biden rematch," she said to applause from a crowd that was roughly the same size as a Trump event in Portsmouth the night before.

Haley brought up Trump 11 times in her speech, a sharp increase from an event in Iowa in late December when she mentioned him only three times, once in a complimentary fashion.

"She really made a pivot toward Trump and made an even stronger case against him because, increasingly, it is a binary choice for voters," said one campaign official, who requested anonymity to discuss internal strategy.

Trump has repeatedly called Haley disloyal for running for president after saying she would not compete with him, and he has called her a poor negotiator during her time at the UN.

Despite Haley's shift in tone, she is still pulling punches. She rarely references Trump's actions to overturn his 2020 election loss to Biden. Most jabs at Trump are paired with attacks on Biden.

Fergus Cullen, a former chair of the New Hampshire Republican Party and a vocal Trump critic, said Haley should be hitting Trump harder for his conduct on Jan. 6, 2021 when his supporters stormed the Capitol building in Washington, and for his attempts to overturn the election, in order to rally more independent voters to her side.

"She's been too timid," Cullen said.

But Frank Sienko, a retired IT worker who voted for Trump twice, said at Haley's Hollis event that he wasn't interested in hearing her talk more about Trump's moral failings and legal issues.

"I've heard enough of that stuff," he said.

In interviews at Haley events this week, eight voters, including Republicans and independents, said Haley's lack of drama and forward-looking mentality appealed to them.

"She can really unify people," said Michelle Wright, 53, of Rye, New Hampshire.

(Reporting by Gram Slattery in Hollis, New Hampshire; Additional reporting by Alexandra Ulmer in San Francisco, James Oliphant in Rochester, New Hampshire, and Nathan Layne in Wilton, Connecticut; Editing by Colleen Jenkins and Alistair Bell)

By Gram Slattery