EXCLUSIVE -- It's been nearly two decades since former Sen. John E. Sununu's name has been on the ballot, but if the New Hampshire Republican decides to launch a 2026 campaign for the swing state's open Senate seat, he's confident he can win.

"I'm sure that if we put together a strong team, this is a race that can be won. This is a race I know I can win. And more importantly, it's a role where I know I can make a difference for New Hampshire," Sununu said in his strongest comments to date, in an exclusive national interview with Fox News Digital.

The former senator, who reiterated he'll "make a decision in October" on whether to launch a Senate campaign in the expected competitive race to succeed retiring Democratic Sen. Jeanne Shaheen, said "it's a winnable race for the right person who reflects our state's values, not the values of Washington."

And despite calling President Donald Trump a "loser" in a newspaper opinion piece early last year, Sununu may land the president's support if he runs.

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"President Trump appreciates winners and understands that John E. Sununu puts this race on the map for Republicans," a national Republican familiar with the Senate race in New Hampshire told Fox News Digital.

Sununu is a former three-term representative who defeated then-Gov. Shaheen in New Hampshire's 2002 Senate election. But the senator lost to Shaheen in their 2008 rematch.

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Shaheen announced earlier this year that she wouldn't seek re-election in next year's midterms, and Republicans are hoping to flip the seat as they aim to not only defend but expand their Senate majority. Four-term Rep. Chris Pappas is the clear frontrunner for the Democratic nomination.

After nearly two decades in the private sector, Sununu sounds like someone ready to hit the campaign trail.

"This is an incredibly important race. It's an incredibly important time for the country and I feel it might be the right time to step up," Sununu told Fox News Digital.

He said that "over the last few weeks, people in New Hampshire have reached out. They've encouraged me to run for Senate, because they know how important it is that New Hampshire has the right kind of voice in Washington, someone who will stand up for our state, someone who won't just be a rubber stamp for anyone else, but will represent New Hampshire every single day."

But it's not just New Hampshire voters who may be encouraging Sununu to run.

Top national Republicans, including Senate Majority Leader John Thune, have held conversations with the former senator regarding a 2026 Senate campaign, a source told Fox News Digital two weeks ago.

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Also speaking with Sununu was former Sen. Cory Gardner, chair of the Senate Leadership Fund, which is the top super PAC supporting Senate Republicans. The source added that Thune and Gardner were cautiously optimistic that Sununu would launch a campaign.

Sununu is a brand name in New Hampshire politics. The former senator's father, John H. Sununu, is a former governor who later served as chief of staff in then-President George H.W. Bush's White House. And one of his younger brothers is former Gov. Chris Sununu, who won election and re-election to four two-year terms steering the Granite State.

But the Republican Party has dramatically changed since the former senator last ran for office 17 years ago. The GOP, under the firm control of President Donald Trump and his America First agenda and MAGA movement, has been transformed from a business-orientated platform into a more populist party.

Asked if there's still room for an old-school fiscal conservative in Trump's GOP, Sununu said, "good decision-making, good leadership, never goes out of style. Standing up for your state, standing up for your neighbors and your friends, and the things that make New Hampshire strong never goes out of style. Being an effective voice never goes out of style."

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But some of Sununu's past criticisms of Trump could come back to hurt him if he joins a Republican primary that already includes former Sen. Scott Brown and state Sen. Dan Innis, who are both showcasing their support for the president.

Sununu, along with then-Gov. Chris Sununu, endorsed former ambassador and former South Carolina Gov. Nikki Haley in the 2024 New Hampshire Republican presidential primary, as she battled Trump for the nomination.

And on the eve of the first-in-the-nation presidential primary, the former senator wrote an opinion piece titled "Donald Trump is a loser," that ran in the New Hampshire Union Leader, the state's largest daily newspaper.

"@JohnSununu was the original 'Never Trumper,'" Brown charged in a social media post this month. "He's going to have to explain that."

Brown endorsed Trump ahead of his 2016 New Hampshire primary victory, which launched him toward the GOP presidential nomination and ultimately the White House. Brown later served as U.S. ambassador to New Zealand during Trump's first term.

And Innis claims that he's the most pro-Trump candidate in the race.

Asked if he could win a Republican primary race that could turn into a Trump loyalty test, Sununu said "the real question is, can you be effective? Can you work with other members of Congress? Can you work with this White House? Can you provide the kind of leadership it takes to get things done? And I know I can do that."

"If there's a primary, I've seen them before. I've been through them before," he added. "I'm very comfortable with where we are today, and over the next few weeks, I'll continue to get people's perspective, put together a good team, make sure we have a winning message and make a decision in October."

Trump, whose endorsement in Republican primaries is extremely influential, has remained neutral to date.

And the president may be willing to overlook Sununu's past jabs.

Earlier this year, when Chris Sununu flirted with a Senate bid after leaving office, Trump urged him to run.

The younger Sununu, who was Haley's top supporter and surrogate in New Hampshire, repeatedly criticized Trump during the 2024 Republican presidential primaries.

Trump told reporters in April that he had met with the former governor in the Oval Office and that he'd "support him fully."

"He's been very nice to me over the last year or so," Trump added. "I hope he runs. I think he'll win that seat."

The national Republican strategist, who asked to remain anonymous to speak more freely, said that "aside from his famous last name, Sununu is a serious candidate with the ability to fundraise and appeal to New Hampshire's unique politics. All other candidates -- announced or considering -- will have a very difficult time against Chris Pappas next November."

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Asked about trying to earn Trump's support, Sununu said, "I'd certainly love to have support from across the spectrum, that includes the president."

But he added that "at the end of the day, this is about building support in New Hampshire, providing the right leadership for New Hampshire and the right message for New Hampshire."

Former Republican senator on potential bid to flip swing state seat red: 'this is a race I know I can win'