The overall problem is rooted not only in the party’s inconsistent efforts to reach Latino voters, but also in the particulars of Mr. Biden’s primary campaign. It was a cash-poor operation that was focused on Black voters, a group long courted by the former vice president that turned out to be critical to his primary victory.
Mr. Biden’s Hispanic-outreach operation, like other parts of his campaign, did not really get rolling until the summer, when his lackluster fund-raising operation turned around, and he hired Julie Chávez Rodríguez, granddaughter of the labor leader César Chávez, to oversee it.
Still, the party has seen some successes. The Democratic National Committee invested heavily in microtargeting Puerto Rican voters through the purchase of call lists in 2019, and Mr. Biden owes his surprising strength in Texas and Arizona to strong support from Latino voters.
Democratic officials say they expected that nine million Latino voters will have gone to the polls early by mail or in person, up from 3.7 million in 2016. Many of those voters are new — 500,000 of the two million Latino voters who have voted early in Texas were there for the first time, according to a person who worked on the effort.
Democrats have also recently begun pouring money and resources into outreach efforts, with donors pumping $28 million into three independent expenditure groups aimed at increasing Latino turnout in the past two months. That includes a recent influx of cash from Michael R. Bloomberg, the former New York mayor, and Priorities USA, a leading pro-Biden super PAC.
Thanks to those funds, the Biden campaign has been able to increase its Spanish-language media buys in the closing weeks, with six-figure expenditures booked in Florida, Arizona and Pennsylvania, a spokesman said.
Mr. Biden has also made multiple trips to Florida, and surrogates like Mr. Castro have been crisscrossing the Sun Belt to stoke turnout. Last week the campaign dispatched Kamala Harris, his running mate, for a high-profile tour of the Rio Grande Valley of Texas, even though Mr. Biden himself has not campaigned in the state, a big prize many in his campaign still view as a reach.