Las Vegas, NV -- Mexican-American politicians Joaquín and Julian Castro, both 41, are bookending the first Democratic debate with pro-Hillary campaign events. The support could help Hillary Clinton hold on to her Latino supporters as she facing falling poll numbers in primarily white states and across the nation generally. Congressman Joaquín Castro (D-Texas) spoke at a canvassing event Sunday in Las Vegas, Nevada, where he addressed crowd of 25 mostly Latino volunteers. After his address the volunteers fanned out in a door-to-door to recruit Democrats to caucus for Clinton.

The first Democratic debate won’t take place until Tuesday night, but Clinton is already consolidating support among prominent Latinos. Joaquín Castro endorsed her September of 2014. Former New Mexican Gov. Bill Richardson pledged his support over a month ago. Support from Latinos a (and young Latinos like the Castros) that could help bouy the Clinton campaign. 

Clinton’s money and poll advantage is starting to dip or at least level off. She dropped below 50 percent in the most recent national poll. Her fundraising is still strong, but on par with Bernie Sanders who isn’t even using PAC money.

One way to keep her momentum up is to lean on existing victories in the theater of field organizing and endorsements.

Julian Castro, the former San Antonio Mayor who currently serves as Obama’s director of HUD, will formally endorse Clinton on Wednesday. Julian is an oft-discussed choice of VP for Clinton.

“My brother is proud to support Hillary he believes that she would make the best president of the United States, Democrat or Republican. So he's going to do everything that he can of course to help her win,” Joaquín Castro said.

Clinton has also entrenched her advantage in an early ground came. While lesser-known candidates are hoping to introduce themselves to Democratic voters at the debates, Clinton already has people introducing her door-to-door.

Joaquín Castro told reporters that even in the era of social media and cable news person-to-person organizing efforts are still crucial for getting out the vote. It’s all about getting existing supporters to spread their enthusiasm.

Ground Game Advantage

Take Juana Aguilar, 33, who canvassed for Clinton at the Castro event. The Las Vegas Democrat chose Obama over Clinton in 2008 but says that this time around, she’s ready for a female president.

"To be honest... I'm not sexist but... [I support her] because she's a woman. I have a feeling that it's time for a woman," said aguilar, who brought her high-school-aged son and his three friends to the event.

Aguilar’s mind is already made up, and that’s bad news for candidates like Martin O’Malley and Bernie Sanders who are looking to grow their support among Latinos. But it’s also very early in the nomination process, and Clinton has already shown a number of weaknesses.

Clinton already has boots on the ground. Even if it was just 25 people in one neighborhood, watching a Hillary supporters makes one think that her opponents will be playing catchup on Tuesday. 

Yet Latino voters in Nevada and around the country will watch this debate with a critical eye as Democrats vie for their support in the nomination race. Many complain that promises on immigration reform have not been kept in the past. Even Latino politicians need to be held accountable, voters and activists say.

“Don’t forget that the two of us are Mexican,” one elderly Clinton supporter told Joaquín Castro in Spanish as she left the event, her blue dress swishing below her broad'brimmed hat.

“She’s basically saying ... don’t forget your roots,” Castro said. “Each of us in our own lives try to strive to remember where we came from. [No matter your job] it’s humbling.’  

The Castros are second generation Mexican-Americans.