/ Updated 
By Suzanne Gamboa

WASHINGTON, DC -- Back home on visits with his parents in southern California, José “Pepe” Gil usually speaks Spanish, even though he is fluent in English.

When he’s teaching English as a second language through his church, the 23-year-old Washington, D.C. resident uses Spanish to help students learn. And with friends, “it’s common we’ll tap into Spanglish, particularly with slang,” Gil said.

He is what is often referred to as a bilennial, a millennial for whom the two languages and all their cultural resonance are intertwined with his identity. Gil is the sort of voter the Hillary Clinton campaign said it is trying to reach with messaging tailored to reflect the bilingual, bicultural world of Latino millennials.

Jose "Pepe" Gil, is a "bilennial" who is comfortable going between English and Spanish.Jose "Pepe" Gil

“There’s something we’re now using, bilennials, as the way to talk about bilingual millennials," said Lorella Praeli, Clinton’s Latino outreach director, who is 28 and bilingual.

She said there has been growth in the last four years of millennials more comfortable with English or more comfortable with Spanish, "but really now they want you to communicate with them and not make them pick a side,” Praeli said.

But while Clinton has solid backing from Latinos - 71 percent among likely Latino voters, according to the latest NBC News/Wall Street Journal/Telemundo poll - she hasn't been able to energize younger Latinos to the degree her rival in the primaries, Bernie Sanders did.

RELATED: Clinton Losing Millennial Support Nationally and In Key States

"It's an important constituency for her and to date it doesn't seem she's been able to bring on board all Bernie Sanders' supporters. Some are going to third party candidates. She is struggling a bit," said Stella Rouse, director of the Center for American Politics and Citizenship at the University of Maryland.

It's a worry considering that 44 percent of the Latino electorate is millennials, according to Pew Research Center, which defined the generation as ages 18-35.

Gil, born in the U.S., said campaign messaging that recognizes his bilingualism and biculturalism would get his attention.

“Anything that I receive that attempts to get me to vote —to tap into who I am and all that encompasses, I would appreciate,” Gil told NBC Latino.

But at this point, he's decided to vote for Clinton. “Most definitely," he said.

Kevin Abreu is a "bilennial," a bilingual millennial. A college student, he lives in Newark, N.J.Kevin Abreu

Kevin Abreu, 21, of Newark, New Jersey, said outreach that recognizes his bicultural background would make him feel "connected," like the candidates are trying to reach a larger demographic.

Abreu often spent summers in the Dominican Republic, where his grandparents and many relatives still live. Spanish was his first language and the only language he uses to speak to his parents. His English came in his first years at school, with the help of shows like Sesame Street and from teachers. Now a student at Montclair State University in New Jersey, he also works as a production assistant at an English language television show.

He said hasn't decided who'll get his vote, but outreach tailored to him as a bilennial would make him think about voting for Clinton.

"It makes me feel they are trying to bridge a gap and they are listening to some of the concerns we have," said Abreu, who was born in the U.S.

Elevating Appeals to Young Voters

With polls showing shaky support for her among millennials, Clinton has elevated her appeals to the age group. In a speech Monday, her message to the nation's youth was they could not afford to stay home.

"There’s no doubt in my mind that young people have more at stake in this election than any other age group and when you turn out and vote this fall, we will be sending a message much larger than even the outcome," she said.

Come Election Day on Nov. 8, some 12 million Latino millennials, people ages 18 to 35, will be eligible to vote. That's more than the total Latinos who voted in 2012 (11.2 million) and about as many who chose not to vote (12.1 million). But historically, the majority of young Latinos have skipped the polls.

In a July GenForward/Black Youth Project/AP/NORC Center survey, just 43 percent of Latinos 18-30 said they would vote for Clinton if the election were held at the time of the survey, July 9-20. That was compared to 57 percent of young black Americans and 50 percent of Asian Americans who said they'd vote for her. Just 25 percent of young white Americans said they support Clinton.

In the same survey, 17 percent of Latinos queried said they would probably not vote.

María Teresa Kumar has spent more than a decade trying to engage bilennials as the founding president and CEO of Voto Latino. She said they are the hardest demographic to reach. Voto Latino is trying to mobilize as large a share of Latino voters as it can get, she said.

"Our challenge is trying to undo the harm done by Bernie Sanders and that is a challenge," Kumar said. The harm, she said, was his speechifying over a "rigged" system as his nominee prospects dwindled.

She said her organization sees evidence, from Twitter feeds and social media and when Voto Latino talks to young voters, that young people are wary about our political system.

RELATED: Clinton Losing Millennial Support Nationally and In Key States

Hacked emails that showed some Democratic National Committee staff favored Clinton may have undermined the Democratic process, said Kumar, but she said the staffers' actions were not the equivalent of of changing ballots to rig an election.

"If you have a first-time voter and you are enthusiastic and a candidate shares your vision and he loses and says the system is rigged — all you've done is you've made our work harder," Kumar said. "Our job is to go where they are and convince them otherwise."

Targeting Young Voters, the Bicultural Way

Millennials have been seen as more multicultural than other generations for a few years. Multicultural marketing, though not new, has taken on added significance because of the demographic overlap of millennials and Latinos. About a fifth of all millennials are Latino.

Clinton's campaign is trying to emphasize to bilennials that there is a stark difference between the two presidential candidates, especially when it comes to embracing bicultural and bilingual Americans.

During the primary debates, Donald Trump criticized Jeb Bush for speaking Spanish on the campaign trail and equated it with failing to assimilate. “This is a country where we speak English, not Spanish,” said Trump in a debate.

Not so for Peruvian-born Leslie Prado, a physician assistant who speaks either language or both depending on what group of people she's with or the setting she is in at the time. Prado, 31, said she lived in a house full of Spanish speakers - her mother, her grandmother and her aunt, her siblings and a 12-year-old nephew who knows that in order to speak to his grandmother he has to use Spanish.

Photo of Leslie Sofia Prado.Leslie Sofia Prado

Growing up in Connecticut, she spoke Spanglish with Puerto Ricans and Dominicans and other Peruvians in her community. She would say “el parking” and “checkiar."

In this, she is far from unusual for a young Latina. In a 2009 Pew survey, 70 percent of Latinos ages 16 to 25 at that time said they use Spanglish.

“When someone I know is very fluent in Spanish, for some reason, we just eventually end up speaking Spanish. If someone in the group is stronger in English, we go back and forth,” she said. “It depends on comfort levels, how fluent they are. We’ll switch back and forth … It’s a flow.

RELATED: Social Media Networks Launch Voter Registration Drives

About 33.2 million U.S. Latinos speak English proficiently, a number that is growing. About 36 million speak Spanish at home, according to Pew.

Lulu Espinosa, 33, works in medical billing and coding and lives in a suburb north of Dallas where she says few of her friends are Spanish speakers. Her husband and her two children also don’t speak it.

Photo of Lulu Espinosa.Lulu Espinosa

But when she speaks to her mother who migrated to the U.S. in her 20s, she speaks Spanish.

Espinosa said she’d welcome a mailing or a call that was in Spanish or a mixture of the languages. She said she sees it as the campaign trying to reach a broader audience and be more inclusive.

Prado agreed. She compared such outreach to World Cup commercials: You may not understand what everyone is saying because they are speaking in many different languages, but you know they are all watching the World Cup. “You just feel connected."

Follow NBC News Latino on Facebook, Twitter and Instagram.