"We're on the verge of possibly the largest Latino voter turnout in American history, and not just because of our community growing, but also because of the emotion that's involved in the election this year, probably more than ever," said Matt Barreto, UCLA professor and co-founder of the research and polling firm Latino Decisions, speaking at a Latino voter forum at the Center for Latin American & Latino Studies and the Center for Congressional and Presidential Studies at American University in Washington, D.C.

The emotion Barreto is referring to is largely related to Republican candidate Donald Trump. When he announced his candidacy he said Mexicans were rapists and drug dealers, and has repeatedly said he would build a wall on the U.S.-Mexico border and would stop "all illegal immigration." That's the impetus driving Latinos to the polls, said Barreto, who is doing polling for the Clinton campaign along with political scientist Gary Segura.

"Immigration is a mobilizing issue. When people think that their personal welfare is at stake, they are more likely to participate," Barreto said. "In the Latino community, there are few issues that can evoke emotion more than immigration."

Latinos of course care about other issues, but immigration is different, said Barreto. "On the economy, for instance, all candidates say the same thing; that they want to make the economy better, but that's not the case with immigration. It's an issue where the contrast is very clear. Voters can easily map their preferences on the candidates."

Polls by Latino Decisions and Pew Hispanic have found most U.S. Latinos support a pathway to immigration reform. Pew Hispanic found that more than 36 percent of registered Hispanic voters would not vote for a candidate who disagrees with them on immigration, including a quarter of Latino Republicans and four-in-ten of Hispanic Democrats.

It really is not anything new and it is not limited to Trump, said University of Maryland political science professor David Karol. It is rather a long-festering issue that the Republican party is just now grappling with.

"Donald Trump didn't come out of nowhere. Trump has inherited a lot of support within the Republican Party that is a result of actions taken by Republican leaders over many decades," Karol said. "There's (GOP 1964 presidential candidate) Barry Goldwater coming out against civil rights legislation, there's Proposition 187 (in California), and the rise of the Tea Party after Obama was elected," he said.

"President George W. Bush tried to reorient the party with his 'compassionate conservatism.' He pushed hard for immigration reform but the base of the party rejected it," added Karol. "The Republicans who do want to target Latino voters are very constrained by the base."

Latino community activists say that impetus to get involved and vote this year is also fueling efforts to reach young Hispanic voters.