As Kelly Ayotte prepared for her first campaign speech, as a candidate for Senate in 2009, she was nervous, but not about her message.

“I’m worried about my voice thing,” she confided to an aide, pausing during a run-through. “My voice tends to do this cracking sound.”

“ "I call them like I see them, and that means not just with the opposing party, but with my own party." ”

Today, Ayotte’s voice is still distinctive — she seems to speak more from her throat than her diaphragm — but her words are resonating.

She has attracted public notice with her sharp criticism of the administration's response to the 2012 attack on the U.S. Consulate in Benghazi, in which four Americans died. She has pushed for a thorough investigation and was among a group of senators who last month demanded a meeting with White House officials to discuss the incident.

Meanwhile, she has broken with her party's conservative base on a host of other issues, including immigration reform. Ayotte notably supported a Senate compromise that would create a pathway to citizenship for undocumented immigrants at the same time that border security is tightened, a proposal that has been met with wariness by House Republicans who fear that border security will be neglected if the measure is passed.

At 45, Ayotte is the youngest woman in the Senate, and as a prominent conservative woman she is often mentioned as part of a potential Republican national ticket. But her trajectory to this point has been startlingly short; five years ago, she hadn’t ever run for office.

In New Hampshire, the attorney general is nonpartisan and appointed by the governor -- and Ayotte was appointed three times, once by a Republican and twice by a Democrat. She was the first woman to hold the position, which some associates described as her dream job.

But when Sen. Judd Gregg, R-N.H., decided to retire at the end of his term, in 2010, Ayotte was his pick to replace him. Gregg met with her in New Hampshire to urge her to run, as did Sen. John Cornyn, R-Texas, then chairman of the National Republican Senatorial Committee.

Ayotte wasn’t sure she wanted the job — particularly with two children at home, then aged 2 and 5.

“She wasn’t gung-ho right out of the gate,” said one Republican familiar with the early recruiting process. “It definitely took some, 'We need you, the country needs you, the state needs you.'"

The lure of public service was strong for Ayotte and her husband, Joe Daley, a former military A-10 pilot. Ayotte resigned as attorney general and launched a campaign.

Although she had the blessing of the NRSC, Ayotte didn't have strong ties with Republicans in her own state. In an interview with the Washington Examiner, she could recall only a single Republican meeting she had attended before she ran for Senate.

And, in a primary race against wealthy candidates who could fund their own campaigns, Ayotte had neither a network of donors nor any experience raising money.

Ayotte and her husband, whose landscaping and snowplow business was now the sole source of income for their family, sat down together and drafted a list of 1,000 people whom they could ask for $100.

They doggedly worked this simple strategy, and it paid off. “That’s how you get your first $100,000,” Ayotte said.

If Ayotte's early fundraising was stronger than expected, her polling was less impressive. Activists resented her for campaigning like a front-runner, and her ties to the NRSC were a liability during the 2010 Tea Party wave. By early summer 2010, with the primary election in September, the outlook was dire.

“The race was a mess,” said one New Hampshire Republican strategist with close ties to Ayotte. “She was going to lose.”

Ayotte put in a call to her close adviser, Rob Varsalone, a veteran of New Hampshire politics who was then working overseas, and asked him to return. He agreed — and the campaign started to shed its made-in-Washington air.

“People really liked her, and when they met her, they wanted to support her,” said Periklis Karoutas, who helped lead the campaign of one of Ayotte’s major challengers, businessman Bill Binnie.

With less than one week before the primary election, the Republican candidates gathered onstage for a final televised debate. The moment demanded a stellar performance by Ayotte.

During the debate, Brooks Kochvar, Ayotte’s campaign manager, and former Gov. Steve Merrill, a close adviser, watched from the green room. They broke an hour of silence only at the very end, with a triumphant high-five.

A few days later, Ayotte eked out a victory by fewer than 2,000 votes.

“It’s really a baptism by fire when you get into a Senate race for the first time,” said Jim Merrill, who ran the campaign of another challenger, Ovide Lamontagne, who finished second to Ayotte. “You find your voice and you become a better candidate on the stump, and she did. You could see her grow into the leader you see today.”

Ayotte has been on a steep learning curve since her election.

Before she became a go-to surrogate for Mitt Romney during the 2012 presidential election, Ayotte didn't know whether to endorse a Republican candidate at all.

“She was new to the whole arena, and she was a little unsure of herself, a little unsure of the process, unsure of what the rewards would be, uncertain of the right path to take,” said one New Hampshire Republican operative.

It took a personal appeal to her husband from New Jersey Gov. Chris Christie to begin to seal the deal. A meeting among Daley, Ayotte and Romney followed, and Ayotte endorsed Romney in a surprise announcement soon after.

When he won the Republican nomination, Romney ultimately considered Ayotte as a potential running mate, although she was not vetted. Among the campaign’s concerns was her lack of experience.

“I think I would have been ready,” Ayotte told the Examiner. “Certainly I’m someone who’s worked hard in the Senate, even though I was relatively new there. I had run an office as attorney general. But that wasn’t for me to judge.”

Ayotte has shaped her role as a senator much like she approached her campaign: with the discipline and deliberate work ethic of a prosecutor. She has, as the third amigo to Republican Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., made foreign policy her cornerstone issue, and Ayotte appears frequently on cable news and Sunday morning television programs to share her views, most recently regarding Ukraine's political turmoil.

And Ayotte has largely avoided political drama — except on matters she considers vital.

A few months ago, with a government shutdown looming as Sen. Ted Cruz, R-Texas, threatened to hold up funding in a quixotic effort to unwind Obamacare, Senate Republicans met in the Capitol for a regularly scheduled strategy session.

The closed-door meetings are not often entertaining and rarely fiery — but on this day in October, Ayotte was explosive. She assailed Cruz for backing Republicans into a political corner, and she criticized him for working with outside groups that sought to unseat Republican senators.

“I call them like I see them, and that means not just with the opposing party, but with my own party,” Ayotte explained in an interview. “I just thought the shutdown was the wrong strategy.”

The standoff drew headlines, but Ayotte wasn’t out of character: Her independent streak is central to her brand as a lawmaker. And the party has begun to pay notice.

Later this month, Ayotte will moderate a discussion among Republican candidates at a mega-donor confab in Colorado, hosted by the prominent GOP moneyman Paul Singer.

“I look at it as an opportunity for me to support our Republican candidates and our party, to help us get a majority in 2014,” Ayotte said.

Ayotte is looking not only to 2014 but also to another high-stakes election: her re-election bid in 2016, when strategists in both parties predict she could face a fight for her political life against Democratic Gov. Maggie Hassan. In a recent Public Policy Polling survey, Ayotte led Hassan by 6 points.

“If we have a candidate with a pulse in a presidential election year, Ayotte doesn’t have a shot,” said one New Hampshire Democratic strategist.

Ayotte isn't taking any chances, and she has been privately working to recruit a strong Republican candidate to oppose Hassan for governor this year.

And since the day after Ayotte was elected to the Senate in 2010, a small group of her closest allies has worked to ensure she will be competitive. The advisers — former Gov. Merrill, former Gov. Craig Benson, Varsalone, and Steve Duprey, a former New Hampshire GOP chair — have been laying plans for campaign strategy and staff, mapping out the potential political landscape, and running vote models.

Ayotte had other plans for that day after the election: to stand on a busy street corner in Manchester, N.H., and thank her constituents.

“I thought she was joking,” Kochvar said.

She wasn’t — and Kochvar and a handful of campaign staff stood outside holding signs that read, “Kelly says thanks.” Ayotte joined them, smiling to cars and passersby, with a sign reading, “Thanks NH.”

The glow hasn’t subsided.

“I have to pinch myself sometimes,” Ayotte said. “The ability to serve first as attorney general and then as a U.S. senator is certainly more than I could’ve hoped I’d accomplish ... I really don’t have ambitions beyond this.”