There are undoubtedly other factors as well. For example, across ethnic lines, people with college degrees are more likely to vote, and Latinos lag behind non-Hispanic whites in higher education. They also have disproportionately higher rates of poverty, which is associated with decreased voting.
Which races have Latinos given an edge to?
If Latinos are the primary key to turning California blue, as many people in the state say, it’s fair to argue that they can sway any election when the candidates are closer than 10 percentage points apart in the polls.
A clear example is the area now covered by the 36th Congressional District, where Raul Ruiz won in 2012 in large part by focusing on the growing Latino population in the district, which includes part of Palm Springs and other large swaths of the Coachella Valley. Before his victory, the area had not been represented by a Democrat since the 1980s.
Change came even more quickly in Orange County, when Loretta Sanchez defeated a longtime Republican congressman, Bob Dornan, in 1996 in a district that is now seen as solidly Democratic. But that trend has yet to take hold in the wealthiest parts of Orange County or in the reliably conservative Central Valley.
Democrats and Republicans have a mixed record of focusing on Latino voter turnout. Mr. Barreto said there has been a general reluctance to spend money for Spanish-language campaign advertising, which often boosts Latino turnout. But he said there were “very early signs” that those attitudes were changing, and that Democratic groups in particular were willing to invest money in getting Latinos to the polls for the midterms.
Where will Latinos matter during this election?
It depends on how many show up to vote. Antonio Villaraigosa once personified Latino political power — he was the first Latino elected mayor of Los Angeles in modern history. But his campaign for governor has struggled. He is counting on a large turnout among Latino voters to lift him to the No. 2 spot in the primary, and thus onto the November ballot. But some polls show him getting the nod from fewer than 25 percent of likely Latino voters. While Latinos are generally expected not to turn out as heavily as non-Hispanic whites do, exit polls for state elections in New Jersey and Virginia last year showed that Latino turnout was up modestly compared with past midterm elections.
“If Latinos were turning out en masse for him, he wouldn’t be in the singles,” Mr. Suro said of Mr. Villaraigosa’s poll standing in the crowded primary field. “This is the first credible Latino running for governor in forever. You’d think, if there’s a groundswell of Latinos going and saying ‘here’s our chance,’ you’d see it in the numbers by now.”