WASHINGTON — The nation’s largest Hispanic group kicked off an effort on Thursday to register a quarter of a million new Hispanic voters by the midterm elections in November.

Officials at the group, NCLR, also know as the National Council of La Raza, said they planned to spend $5 million in tangent with Mi Familia Vota, a nonpartisan voter education organization, to target eligible voters.

The announcement comes shortly before House Republicans are to reopen discussions about an overhaul of immigration laws at their annual retreat next week. Gary Segura, a co-founder of the polling firm Latino Decisions, said that if Republicans eased their opposition to immigration changes, the decision could improve their electoral chances.

“The Republicans have a great deal to gain in terms of brand improvement and in terms of essentially demobilizing virulent opposition built around the supposition that they are the impediment to immigration reform,” Mr. Segura said.

Clarissa Martínez de Castro, NCLR’s director of immigration and civic engagement, said Democrats needed to hone their message, too. “I think it’s clear that Democrats need to demonstrate that they can actually deliver on promises made, and that it’s clear that voters need something to vote for, not just something to vote against,” she said.

About 39 percent of Hispanics said that Republicans care “some” or “a lot” about their community’s concerns, according to a recent Pew Research study. About 72 percent of Hispanics said the same of Democrats.

To reach their voter registration goal, NCLR and Mi Familia Vota will mail voter registration materials to more than 2.5 million Latinos in seven states — Arizona, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah — and will make follow-up calls.

The groups will also expand existing registration efforts in California and Florida, although officials did not detail that plan on Thursday.

NCLR has already raised $3 million from private foundations toward the $5 million effort, which Janet Murguía, the group’s president, said was a sign that donors recognize the importance of getting an early start on voter registration drives.

Last year, the Senate passed a bipartisan measure to overhaul immigration laws, and Ben Monterosso, executive director of Mi Familia Vota, said he hoped the new campaign would spur the House to act.

“We expect that the House of Representatives also gets the message and do their jobs, or else our community in November is going to go out to vote con más ganas,” he said, using a Spanish phrase that translates to “with more energy,” adding that Hispanics wanted “to make sure that our interests are being taken care of.”