Sen. Ted Cruz stood on a stage straddling the lanes of a dragway at the Charlotte Motor Speedway on Sunday, speaking directly to blue-collar workers with “calluses on your hands” and railing against the political establishment — prompting cheers and stomps on the metal bleachers.

Meanwhile in Florida, a group of volunteers, including wealthy donors who supported Jeb Bush’s candidacy, was knocking on doors this weekend in Jacksonville, asking voters to cast ballots for Cruz (Tex.) in Tuesday’s Republican primary.

As Cruz hopes to land a knockout blow against Sen. Marco Rubio in Florida and narrow the primary contest to a two-man race between himself and Donald Trump, he is increasingly trying to appeal to two very different groups: working-class voters who may find themselves drawn to Trump, and voters from the traditional political establishment who want to stop him.

[Cruz looks to take on Rubio on the fellow senator’s home turf]

“For a lot of supporters I think it comes down to this sudden reality of a Donald Trump nomination,” said one of the Jacksonville door-knockers, Paul Dickerson, a Houston lawyer who supported Bush but is now backing Cruz, whom he considers a friend. Trump, he said, “would be a disaster for the country and embarrassment for the nation, and Ted is the best chance to defeat Donald Trump.”

Republican presidential candidate Ted Cruz received his first endorsement from a Senate colleague when Sen. Mike Lee of Utah backed him for the party's nomination. (Reuters)

The fit is not a natural one for Cruz, who pillories the political establishment on the campaign trail and wants to blow up what he calls the “Washington cartel” of lobbyists and special interests. He is detested in the Senate — Cruz jokes that he needs a “food taster” in the dining room there — and only one colleague has endorsed him.

But with Rubio’s candidacy sputtering and with Ohio Gov. John Kasich far behind, the establishment is warming to a man who called Senate Majority Leader Mitch McConnell (R-Ky.) a “liar” on the Senate floor. Even Sen. Lindsey O. Graham (R-S.C.), a longtime Cruz nemesis, now says the party may need to unite behind him. And Neil Bush, Jeb Bush’s brother, is supporting Cruz.

Many point to Cruz’s second-place standing in the delegate race and his organized and well-funded campaign as reasons to support him.

[A lot of people just don’t like Ted Cruz. How come that’s okay with him?]

“Most of the people that I know would not have been naturally with Ted,” said Charles Foster, a Houston lawyer who backed Bush in the presidential race and Cruz’s opponent in the Republican primary for his Senate seat in 2012. “. . . Some are reluctant because that’s not where they were to begin with, and some are still sitting on their hands.”

The establishment world is hardly foreign to the Texas Republican. Cruz; his wife, Heidi; and his campaign chairman, Chad Sweet, all worked for George W. Bush and are making overtures to people who supported Jeb Bush, Cruz backers said. Foster said Cruz called him, while Dickerson said the campaign has been quick to extend a “welcoming hand” with no hard feelings. (Cruz’s campaign said there is no concerted effort to woo Bush supporters.)

Cruz is making the same type of overture to voters on the campaign trail, asserting that he is the only candidate who can beat Trump and directly appealing to those who support other candidates. But he is also infusing more populism into his stump speeches — a direct appeal to would-be Trump backers.

The Ohio GOP primary could be the Republican establishment's last chance to stop Donald Trump. (Peter Stevenson/The Washington Post)

“Let me talk for a minute to all the single moms who are here, who are working two or three part-time jobs,” Cruz, clad in a navy jacket with brass buttons, said at the speedway. “Let me talk to all the truck drivers, the mechanics and plumbers and electricians, the union members.”

The candidate’s economic message is largely conservative boilerplate, arguing that the “jackboot of government” hurts growth and jobs. But Cruz has taken to tying this message specifically to individual workers, arguing that they would fare better with fewer regulations and with a repeal of the Affordable Care Act.

“That’s in stark contrast to Donald Trump’s economic plan, which seems to be: ‘Hey, everybody, look. I’m rich. Maybe you can be rich too,’ ” said Cruz spokesman Jason Miller. “When you’re out in real America, people are hurting, and what they care about is putting food on the table and helping their families.”

[A guide to everything Ted Cruz wants to abolish, bar or change]

The campaign is also painting illegal immigration as an economic issue, arguing that blue-collar and low-income Americans are most hurt by an influx of undocumented immigrants.

Vincent Fernandez, 71, a retired tool-and-die maker from Scott City, Mo., attended a Cruz rally in nearby Cape Girardeau. Fernandez said he doesn’t like Trump’s “big mouth” and believes that Cruz will help the economy.

“I think Ted Cruz will look out and support the working men and the working women across the country,” he said. Fernandez gets coffee each morning with a group of men who are working or are retired from blue-collar jobs, and he said their allegiances are evenly split between Cruz and Trump.

Here at the Charlotte speedway, the attendees of the event sponsored by a pro-Cruz super PAC included country singer Aaron Watson, who performed, and C. Boyden Gray, a lawyer and longtime fixture in GOP politics.

In the stands, Missy Groce, 29, a director of marketing from Jacksonville, said she doesn’t like Trump but likes that Cruz wants to stop illegal immigration and that he looks at the issue through the lens of people’s paychecks.

“All the money is going to illegal immigrants,” Groce said, “despite the fact that you work hard every day.”