Mr. Sanders and Mrs. Clinton will appear Thursday in a televised forum on Telemundo and MSNBC. Each will probably face tough questions: Mr. Sanders about his vote against a comprehensive immigration overhaul bill in 2007, and Mrs. Clinton for saying in 2014, amid a crisis in which thousands of Central American children crossed the border and wound up in detention, that they “should be sent back.”

But immigration is scarcely the only important issue.

At a training session for Clinton precinct captains last week in a heavily Latino neighborhood of Las Vegas, Alex Noriega, 23, said she became a Clinton supporter in 2008 because of Mrs. Clinton’s support for reproductive rights. Then 16, she recalled, she went to Planned Parenthood to get the Plan B medication to avoid a pregnancy after having unprotected sex and became convinced that the policies Mrs. Clinton was advocating were essential for women to control their bodies.

Ms. Noriega said she was unimpressed by what she called the “radical” politics of Mrs. Clinton’s current opponent. “I think Senator Sanders has an unrealistic view of how he wants to get things accomplished,” she said.

The candidates, who swept into Nevada over the weekend, made abundantly clear that first-generation voters and other Latinos could play a decisive role here. In Reno on Saturday, Mr. Sanders told hundreds of canvassers that he would push for a path to citizenship for the estimated 11 million people who are in the country illegally.

“I have met people throughout this campaign, young people with tears running down their cheeks, who are literally worried that they or their parents will be deported tomorrow, that they will be separated from their loved ones,” he said.