Newt Gingrich thinks he can revive his debilitated campaign by talking about Alzheimer’s. So at a private fundraiser last week in Newport Beach, Calif., he devoted much of his speech to the disease.

In the audience, it turned out, were four members of the Alzheimer’s Association’s Orange County chapter.

“This is great,” they later told Gingrich, according to an aide. “You get it!”

And with that, the former House speaker — whose campaign has seemed all but dead since his top advisers quit en masse three weeks ago — had won four new supporters.

For most presidential candidates, Alzheimer’s is a third- or fourth-tier subject, at best.

But as Gingrich sees it, Alzheimer’s, as well as other niche topics such as military families’ concerns and pharmaceutical issues,are priorities for passionate patches of the American electorate. By offering himself as a champion of pet causes, Gingrich believes he can sew together enough narrow constituencies to make a coalition — an unconventional one, yes, but a coalition nevertheless.

In this living-off-the-land phase, as he struggles to regain financing and his footing in the evolving 2012 field, Gingrich is trying to find his voice. More often than not, it’s on Fox News Channel, where he promotes his ideas big and small, hoping that something might catch on.

Gingrich’s public schedule last week included no campaign events but featured at least six media appearances: three on talk radio and three on Fox, the cable network where he has appeared on air some 800 times over the past decade as a paid analyst.

On Monday, Gingrich told Fox anchor Neil Cavuto that he is determined to reach “people who are interested in topics other than traditional politics.”

“I’m going to campaign on, how do we deal with Alzheimer’s, which really affects millions of Americans,” Gingrich said. “I want to campaign on issues such as, how do we fundamentally reform the Food and Drug Administration so we can create American jobs with the best new medicines?”

Gingrich’s friends and advisers said the challenge for a candidate who generates a potpourri of ideas is to figure out which ones will resonate.

“Newt has been seen for the better part of 20 years as somebody who can look at problems and come up with conservative solutions to those problems,” said Republican lobbyist Robert Walker, a longtime Gingrich confidant. “The issue that needs to be established is whether or not he’s able to translate those ideas into real action as president.”

Rep. Michael C. Burgess (R-Tex.), a Gingrich endorser, said, “When you’re in the room with him, ideas come up so fast and furious that sometimes it’s a little difficult to grab them.”

One exception, Burgess said, is Alzheimer’s.

“The speaker gets that probably better than anybody else,” he said.

After Gingrich announced his candidacy in May, his first speech was to a convention of Alzheimer’s advocates. There, he warned that the disease could cost the government some $20 trillion over the next four decades. He told the industry group that Alzheimer’s research is “grotesquely underfunded,” and he pledged to invest more public money in finding a cure.

But soon came the headlines about his $500,000 credit line at Tiffany’s. Then he and his wife, Callista, went on a cruise in the Greek isles. And then many of his staffers walked out on him.

Now, angling for a comeback, Gingrich is trying to shift the focus back to his ideas.

He has started talking about his family’s military background as a way to try to reach out to other military families. Gingrich, whose stepfather was an infantryman for 27 years, grew up as an Army brat. He lived in Germany, France, Kansas and Pennsylvania before settling in Georgia. A possible slogan for that effort would be, “Military Brats for Newt.”

He is trying to capitalize on what campaigns call “free media,” appearing on Fox and talk radio as as often as they’ll book him.

“He spent the previous 10 years as a TV panelist, and he has honed his skills,” Gingrich spokesman R.C. Hammond said, even inviting a comparison with former president Ronald Reagan, who honed hisskills in movies and as a spokesman for General Electric.

Of course, Gingrich is not the only candidate seeking to exploit free media. All of his rivals take turns on Fox, and a Fox executive said Gingrich receives no special treatment.

“We don’t necessarily have him on because he rates well,” said Bill Shine, executive vice president of programming. “He’s a presidential contender who’s been in the news.”

Some of Gingrich’s former advisers said they abandoned the candidate because he was not willing to invest enough time on the ground in the early-voting states. Last month, Gingrich visited Iowa once (a recent stop in Indianola) and New Hampshire once (touring a business in Hudson) but did not visit South Carolina.

Hammond said Gingrich instead spent much of June at private fundraisers — “fundraising is a challenge,” he said — and held a telephone town hall that prompted an estimated 12,000 people to call in.

The new campaign manager is Michael Krull, a longtime Gingrich hand who leads what Hammond described as a “scrappy” team of “about a dozen upbeat and cheerful warriors.”

Gingrich, too, is stepping up his pace, saying he plans to spend 16 days in Iowa in July and August, starting with walking in Clear Lake’s July 4th parade.

Still, Fergus Cullen, a former New Hampshire Republican Party chairman, warned that Gingrich would struggle if he is seen as taking shortcuts.

“The candidates who do the best find that there are no shortcuts,” Cullen said. “If Gingrich thinks he can just do it on Fox News, then all he is is an advocate — an advocate for his ideas — but he’s not a presidential candidate.”

Cullen, in an interview last week at his Dover, N.H., home, said he is a fan of Gingrich’s. He pointed to four of the former speaker’s books on his shelf. But, Cullen said, “it’s hard to take his campaign seriously these days.”

In his cable appearances, Gingrich sometimes sounds more like a pundit than a candidate. During a Tuesday interview with Greta Van Susteren on Fox, Gingrich commented on a menu of current events.

On the street riots in Greece: “They are professional anarchists who want to create violence. The best thing the police there can do is lock them up.”

On the debt-ceiling debate in Washington: “Republicans shouldn’t blink and run for the hills. They ought to be calm and say, ‘This is the Obama depression, it is going to get worse under his policies, and we ought to change it now.’ ”

On senators grilling the generals on the Afghanistan drawdown: “I thought Senator [Lindsey] Graham [R-S.C.] did a good job today.”

Then, after a commercial break, Van Susteren asked the question most candidates hear at the get-go:“How is the campaign going?”

“Much better,” Gingrich said, playing up his underdog status.

“If you go back to 1994,” he said, “nobody in the city thought I was going to become speaker.”