Correction: An earlier version of this article said that U.S. immigration rules allow Puerto Ricans and Cubans to immigrate more easily than citizens of other Latin American countries. That is true of Cubans, but Puerto Ricans, who are U.S. citizens, are not affected by immigration law. This version has been corrected.

— She was scheduled to deliver a speech across town in 30 minutes, but she did not know where to go, or how to get there, or exactly what she would say if she managed to arrive on time. Bertica Cabrera Morris revved the engine in her Jaguar and an alarm on the dashboard warned that she was almost out of gas. She grabbed her cellphone to make a call and watched the battery die and the screen go black.

“Papa Dios!” she said. “Are you kidding me? Why is this happening now?”

Morris, 58, had volunteered for one of the most crucial jobs during one of the most crucial moments of this Republican presidential primary. The Cuban-born adviser to Mitt Romney hoped to persuade many of Florida’s 4.5 million Hispanics to support a candidate who has struggled to reach Hispanic voters in part because of his tough positions on illegal immigration. Morris had spent the past week buying Hispanic radio advertisements, cajoling Florida politicians into endorsements, making speeches in two languages and cashing in every favor earned during her 20 years as a political consultant. “Right now, our Hispanic outreach is me,” she said.

She had long been a political player in Orlando, but her value had skyrocketed along with the population around her. The number of Hispanic residents in the United States increased by 15 million during the last decade, four times the national growth rate. Some of the fastest expansion was here in Central Florida, where the Hispanic population doubled and where, for the first time, some counties are now made up mostly of minorities. These are the new swing voters in the swing districts of a swing state — and they are mostly Puerto Rican, Cuban and South American. Their support could decide Florida’s Republican presidential primary on Tuesday.

Morris hoped to win some of them over in part through a single event: a Romney rally scheduled for the next night at a paint factory in a Hispanic neighborhood of Orlando. She wanted the popular governor of Puerto Rico, Luis Fortuno, to fly in and make an endorsement. She wanted the crowd to wave signs in Spanish and Cuban ministers to offer a blessing. “The stakes are as high as they’ve ever been,” she said, so she was swallowing aspirin during the day and lying awake on the couch at night, sick from stress.

She approached a stop sign and changed the battery of her phone. The screen glowed to life, and eight new messages appeared. “Thank God,” she said. She reapplied lipstick and checked her reflection in the rearview mirror: still young-looking for a mother of five young adults, with stylish glasses, diamond earrings and her hair mussed for effect. She drove to her speech on time, brought a crowd of Orange County Republicans to their feet and then returned to the phone messages.

“You’re going to do this for me, okay?” she told a Romney staffer on the phone. “Everything has to be perfect tomorrow. This is my event.”

Morris had spurned other candidates to work for Romney because she thought he had the most in common with Hispanic voters in Florida. His hard line on immigration would not affect most Puerto Ricans and Cubans, she said, because U.S. rules allow Cubans to immigrate more easily and Puerto Ricans are U.S. ciitizens and are not affected by immigration law. Romney had five children, and so did she. They both had run successful businesses. “Hispanic voters care about family values and the economy,” she said. “He’s the most like me.”

She was officially an adviser to Romney’s campaign, but her advice sounded more like instruction and her requests never seemed optional. “I get things done,” she said, and for the next few hours she continued to make calls to plan the details of the next night’s event.

On how Romney should speak about immigration: “We need to make people feel less fearful,” she told another of Romney’s senior advisers. “This is not a business question for a CEO, but a human question. He has to feel it.”

On the clothes she wanted Romney to wear for his speech: “Definitely jeans. No tie. Maybe mess up the hair a little bit, okay? Por favor. We’re casual people.”

On who should come: “I need you to be there,” she told a local politician. “Remember that time I did you a favor? Well, this is your favor for me.”

On the music: “We need something more lively,” she told a friend in Puerto Rico. “Can you send me something in Spanish, something with energy? This event has to remind of us of home.”

Morris had left home at 14, departing Cuba with her mother and whatever clothes they could squeeze into a single suitcase. Her mother had been the president of a heavy-equipment company in Cuba, and Fidel Castro’s regime threatened her business and briefly jailed her husband for his ties to Americans during the Bay of Pigs invasion in 1961. Morris and her mother left behind three houses and most of their relatives, hoping to start over someplace else.

They fled to Spain, then Los Angeles, then Orlando. Morris enrolled in college but never finished. She married and then divorced. She worked at a bank and for the school board before deciding to start a consulting company. In the early 1990s, as the single mother of two children and the owner of a business with only two clients, she saved for a month to make a donation of $1,000 to Jeb Bush’s first campaign for governor. “I thought it might make me noticed in local politics,” she said. Bush decided to meet with Morris and eventually asked her and her children to create and star in his first Spanish advertisements.

Now, 20 years later, Morris entered her office suite on the 15th floor of a downtown high-rise. The walls were decorated with framed photos of her grinning alongside almost every important Republican in the past two decades, most of whom had relied on her help. There were drink coasters from the U.S. Senate and framed invitations to the White House. Her floor-to-ceiling windows offered views across the flatlands of Central Florida, beyond the luxury hotels and the towers of Disney World.

Romney had come here early in his campaign to meet with Morris and later invited her to his lake house in New Hampshire. She had helped engineer his defeat in 2008, working with Sen. John McCain (R-Ariz.) to win 54 percent of the Hispanic vote in Florida compared with 14 percent for Romney. Four years later, she also had developed close relationships with two of the country’s most important Hispanic politicians: Fortuno, the governor of Puerto Rico, “a dear friend,” she said; and Sen. Marco Rubio (R-Fla.), a possible pick for vice president, who often watched Miami Heat games in her living room and stayed in the guest room at her house.

Morris had agreed to help Romney, thinking he gave Republicans the best chance to beat President Obama. Her children were all off starting their careers or away at college; her second husband, Brian, was working on his bucket list, playing golf at their country club and learning blues guitar. Morris, meanwhile, was busy raising money, advising Romney and serving as a co-chair for the Republican National Convention. “It is only getting busier,” she said, “and that’s how I like it.”

Working on behalf of Romney had involved some backlash in the Hispanic community. He wants English to become the official language of government and he opposes the Dream Act, which would open the door to citizenship to illegal immigrants who come to the country as children and graduate from college.

Two groups of Hispanic Republicans had begun protesting his campaign in Florida, encouraging their members to vote for anyone else. Romney had responded by softening his remarks on illegal immigration, explaining that he didn’t want to “round anyone up.” He had asked one of his Spanish-speaking sons to record a television ad, reminded crowds that his father was born in Mexico and tried some Spanish. “Gracias, amigos,” he sometimes said at rallies.

Morris aimed to make him popular in the Hispanic community, at least during one event. Hours before the rally, she sat in her office with a few local activists and scratched out her goals for the event on a yellow legal pad.

Fortuno would make a speech and offer his endorsement.

Speakers would credit a long list of Hispanic politicians in attendance, thanking them by name.

Cuban and Puerto Rican ministers would mingle in their own green room and maybe pray with the candidate, while a few hundred Hispanics held up signs or waved Puerto Rican flags.

“Make this perfect, okay?” she told her team of organizers.

The signs were all in English.

There was no space for a green room, and no time for the candidate to mingle or pray with ministers.

A crowd of several hundred people filled the paint factory, but less than 20 percent were Hispanic. The Romney advance team had decorated the cavernous space with the familiar campaign banners and gigantic American flags; a rotation of Kenny Chesney and Brooks & Dunn blasted from the speakers.

A few dozen elected officials wore suits and stood near the stage, but none of them would be thanked by name. McCain had decided to accompany Romney to the event at the last minute, and his speech threatened to overshadow Fortuno’s endorsement, which remained tenuous unless Romney committed to support Puerto Rico as a possible 51st state.

“Somebody better fix this,” Morris said to a senior staffer, who nodded and reached for his phone. Morris’s face flushed, and she went outside for some air. “This could be a disaster,” she said, shaking her head. She paced for a few minutes until the staffer came back to find her.

“I took care of it,” he said. She wrapped him into a hug.

A few minutes later, McCain walk to the podium arm in arm with the first lady of Puerto Rico, as the first speaker to greet the crowd. “I’m just the lounge act,” McCain said, before introducing “the people this is really about.”

Morris watched from near the stage as Puerto Rican music started to blast from the speakers. Fortuno and Romney emerged from behind a curtain. They stood side by side at the podium, turning to nod, smile and applaud for each other.

“The great governor!” Romney said, gesturing to Fortuno.

“The great governor!” Fortuno said, gesturing back at Romney, a former governor of Massachusetts.

Fortuno said a few words in Spanish, alluded to Romney’s support for Puerto Rican statehood and made his endorsement. “Wow, this is huge!” Romney said. They stood together onstage while Romney stuck to his talking points, asking veterans to stand and be recognized, and reciting some of the words from “America the Beautiful.”

The men walked off to a standing ovation and found Morris backstage, waiting for them. She was confident the event would sway some of the voters. Romney reached out to hug her. Fortuno leaned in to kiss her on the check.

“Thank you,” the men said.