HOUSTON — Stevens Orozco awoke before dawn on Wednesday, as he does each weekday, and headed to the charter school where he teaches health and psychology. His middle and high school students were taking state-mandated exams, which meant a light day for the second-year teacher.

After dismissal that afternoon, Orozco bolted to his car, grabbed a handful of campaign flyers and drove to a community center on Houston’s northside. The parking lot was teeming with election volunteers and voters who had come to cast early ballots in Texas’ Super Tuesday primary elections.

Orozco, 33, the son of undocumented Colombian immigrants, waved for a woman to stop her car as she pulled up to the voting site.

“My name is Stevens Orozco, and I’m running for Congress here in District 18,” he said, handing her a glossy flyer with his picture on it. “I’m running on the most progressive agenda, taking no corporate donations. I support the Green New Deal, ‘Medicare for All,’ student loan forgiveness and immigration reform, as well as reparations for slavery and criminal justice reform. And I would appreciate your vote today.”

Orozco hopes to win voters with an aggressive agenda to combat climate change, expand access to health care and reform the criminal justice system. Annie Mulligan / for NBC News

After repeating variations of those lines thousands of times in recent months, Orozco can deliver the pitch in under 15 seconds. The woman smiled and committed to supporting him.

“It feels good when they say yes,” Orozco said a moment later. “Usually they don’t say anything and you’ve just got to hope the message resonated.”

That’s the question facing Orozco and other Democratic candidates who share his fervent progressive views: Is the message resonating with voters? He’s part of a wave of young, unapologetically left-wing candidates who are mounting primary challenges against older Democratic incumbents in solidly Democratic congressional districts and local races, in Texas and across the country.

These candidates are inspired by the anti-establishment message of Sen. Bernie Sanders, who has the most delegates in the race for the Democratic presidential nomination, and by the rise of Rep. Alexandria Ocasio-Cortez, the 30-year-old democratic socialist who became a national star when she unseated a 10-term incumbent Democrat in New York City two years ago. Many are millennials and political newcomers, motivated by their experiences coming of age amid the 2008 financial crisis. Others got started as activists on the front lines of battles over police brutality, gun violence, climate change and immigration.

And like Orozco, most are facing extraordinarily long odds of victory. Orozco is challenging Rep. Sheila Jackson Lee, a Democrat running for a 14th term, who has a long-standing reputation as one of the more liberal members of Congress, though Orozco argues she has not gone far enough on issues such as climate change and immigration reform.

“They are long-shot bids, sure, but so was AOC,” said Brandon Rottinghaus, a political scientist at the University of Houston, referring to Ocasio-Cortez by her now-famous initials. “So the prospect of catching lightning in a bottle again is what many of these candidates and these groups are looking for.”

In South Texas, Jessica Cisneros, a 26-year-old immigration attorney, has been endorsed by both Sanders and Ocasio-Cortez in her campaign to unseat Rep. Henry Cuellar, a 64-year-old pro-gun, pro-trade centrist backed by the Democratic Congressional Campaign Committee and House Speaker Nancy Pelosi.

“We want this to be not only a victory, but a resounding victory for Henry Cuellar,” Pelosi told a crowd of Cuellar campaign workers and supporters during a stop in Laredo last week.

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Jessica Cisneros, a 26-year-old Democratic candidate for Congress in Texas' 28th district, has been endorsed by leading progressives, including Sen. Elizabeth Warren. Nick Wagner / AP

The race is considered the first serious challenge against a Democratic incumbent of the 2020 election cycle. In some ways, the contrast between Cisneros and Cuellar reflects the broader ideological rift defining the Democratic presidential primary, with Sanders and Sen. Elizabeth Warren pushing aggressively left-wing policies, while others, such as former Vice President Joe Biden and former New York Mayor Mike Bloomberg, are taking more centrist positions.

Cisneros said she’s running to give a voice to a new generation of voters who are eager for sweeping changes in Washington.

“One of the most encouraging things about running is seeing how younger folks have responded to our race,” Cisneros told Vice News this week.

Moderate Democrats aren’t the only ones being targeted. In another Houston race, Rep. Al Green, who made national headlines as the first House Democrat to call for President Donald Trump’s impeachment, is facing a primary challenge for the first time since being elected to Congress in 2004, from a 36-year-old mortgage broker, Melissa Mechelle Wilson, who says she’s running to expand affordable housing and overhaul the criminal justice system.

“You can do a great job and still get an opponent,” Green told the Houston Chronicle, when asked about the new primary challenges. “The system allows for that. I respect the system.”

Rottinghaus said these progressive challengers remind him of the political revolution of the 1960s and ’70s, when a new generation of candidates and young voters, outraged by the war in Vietnam and the Watergate scandal, pushed for a vast expansion of civil rights and environmental reforms. As was the case then, Rottinghaus said, progressive candidates could succeed in moving the Democratic Party further to the left, even if they failed to win many seats in the process.

“They don’t want to wait, and this is in their opinion a moment that can lead to this full-scale revolution in the way the Democratic Party handles these issues,” Rottinghaus said. “These progressive challengers are looking for a different type of approach, a more aggressive approach to the issues.”