DUBLIN, N.H. — “ I’m sick of Republicans letting Obama walk all over them,” says Denise Roberts, a Dublin, N.H., Republican who has come to a grand old home in the shadow of Mount Monadnock to get a first-hand look at Sen. Ted Cruz, perhaps the hottest might-be-candidate in the GOP 2016 presidential field.

Cruz, says Roberts, isn’t afraid to stand up to Obama, or anyone else. “I would vote for him for president from here until 2016,” she declares. “I agree with him, big time.”

Roberts isn’t alone among Republicans these days, certainly not in New Hampshire. “I’m so tired of the old school, like McCain and Graham, I’m tired of those guys,” says Jonathan Brooks, from Merrimack. “I’m excited about Cruz. I’m interested in his brand of politics.”

“Cruz isn’t going to do that back-and-forth, one minute he’s saying he’s a conservative and the next minute he’s selling us out completely,” adds Marilyn Huston, of Keene.

Cruz has ostensibly come to New Hampshire — his first-ever visit — to help the state Republican Party raise money. But he’s made two previous trips to Iowa this summer that left conservatives there buzzing about his presidential prospects. Now, he just happens to be appearing in the nation’s first-primary state. Some of his speech at the summer home of longtime New Hampshire party stalwarts Joseph and Augusta Petrone is focused on his crusade to defund Obamacare. But it’s also a campaign speech — not so much for himself specifically but for the new wave of Republican politicians of which he is a part.

“Something incredible is happening, I am convinced,” Cruz tells the crowd. “We are seeing a new paradigm in politics that is changing the rules. And that new paradigm is the rise of the grassroots.” Energized conservatives have empowered newly-arrived leaders like Rand Paul, Mike Lee, Marco Rubio, and of course Cruz himself, to stand up against not only Barack Obama but against all those old, entrenched Republicans who aren’t up for the fight.

Cruz explains that grassroots power was behind his own improbable victory in the 2012 Texas Senate race. It was behind Rand Paul’s filibuster against Obama administration drone policies. It was behind the GOP’s successful effort to stop Obama’s post-Newtown gun control initiatives. And it has brought “hope and optimism” to discouraged Republicans.

Cruz’s discussion of guns in particular shows how he has tweaked his message from recent speeches in Iowa and his home state of Texas. Before coming to the fundraiser, he met with a group of local county officials, for a little New Hampshire Politics 101. A couple of hours later, when he spoke, the audience heard a little less God and a little more guns.

Cruz noted that hostess Augusta Petrone has a sign in her home that says, “Stop Crime — Shoot Back.” That, Cruz added, “is really how you make a Texan feel at home.” Cruz also took a shot at New York City Mayor Michael Bloomberg, who has brought his gun control crusade to New Hampshire. “Any New York mayor…” — the crowd starts booing at the first mention of Bloomberg — “who thinks he can come up here and bully the senator from New Hampshire seems a little confused by the concept of 'Live Free or Die,'” says Cruz.

It works; this is a crowd that cares a lot about the right to bear arms. How much? Des Ford, from Hancock, explains that, “Our Christmas stockings were hung off my father’s musket ever since I was an infant. They still are.” He worries that New Jersey Republican Gov. Chris Christie is “questionable on the Second Amendment.” Then he adds: “Cruz is not. He’ll do well here.”

But Cruz is doing more than pleasing the crowd when he talks about guns. He uses the Senate fight as example of how Republicans, if they are united, can stop seemingly unstoppable forces. “In the early days and weeks, that fight looked unwinnable,” Cruz says of the gun-control battle. “The momentum was entirely with the president.” And then “a handful of senators stood up.” Those few lawmakers ignited the grass roots, who pressured wavering Republicans. Pretty soon the momentum was with the opponents, and Obama’s gun control measures were stopped in their tracks.

The analogy is obvious. Sure, defunding Obamacare looks like the longest of long shots today, Cruz argues, but the grassroots can do anything. They can even force recalcitrant, or just plain cowardly, senators into joining the Obamacare-defunding movement. And even though there are only 14 (out of 46) Senate Republicans on board at the moment, Cruz tells the crowd that anything is possible, if “millions and millions” of Americans rise up and tell their lawmakers what to do. He asks everyone to go to a new website, Dontfundit.com, to sign a defunding petition. So far (as of Sunday evening) the site had about 550,000 signatures — not millions and millions, but not nothing, either.

Cruz’s enthusiasm makes for a few awkward moments with his Senate colleague, New Hampshire Republican Kelly Ayotte, who introduced Cruz and is standing in the crowd watching his speech. Ayotte, of course, is one of the 32 Republican senators who have not signed onto the defunding Obamacare initiative, and she was also strongly opposed to the Paul/Cruz/Lee/Rubio drone filibuster. When Cruz discusses the defunding plan, tossing in several applause lines, Ayotte doesn’t seem to know what to do with her hands. Mostly, she doesn’t join in the applause, but every now and then she claps a little, even though Cruz is outlining proposals she rejects.

But the larger point of Cruz’s presentation is not really Obamacare, or guns, or drones. It’s standing up to Obama. Does everyone in the audience believe that Republicans, with a minority in the Senate and a Democrat in the White House, can succeed in defunding Obamacare? Not at all. But they’re almost indescribably eager for a Republican to take a stand, and that’s what Ted Cruz is doing.

Cruz does seem genuinely unafraid. He’s certainly not afraid to alienate some of his fellow Republican lawmakers, or cause Democrats and some in the media to call him crazy. To many in the GOP base — the grassroots — he’s antagonizing all the right people.

Of course, fearlessness is not the same as judgment, or wisdom, or a number of other qualities that would be good for a president to have. But it’s high on the Republican list now because so many in the GOP have been so disappointed for so long by their leadership. That’s what’s driving enthusiasm for Cruz’s possible candidacy at the moment, and what might drive it a lot more in the future.