Florida Republicans are poised to adopt one of the nation’s most aggressive congressional maps, pressing forward with a proposal from Gov. Ron DeSantis that would most likely add four congressional districts for the party while eliminating three held by Democrats.
The map, which the Florida Senate approved by a party-line 24-to-15 vote on Wednesday during a special session of the Legislature, was put forward by Mr. DeSantis after he vetoed a version approved in March by state legislators that would have added two Republican seats and subtracted one from the Democrats.
The new proposal would create 20 seats that favor Republicans, and just eight that tilt toward Democrats, meaning that the G.O.P. would be likely to hold 71 percent of the seats. Former President Donald J. Trump carried Florida in 2020 with 51.2 percent of the vote.
The Florida map would erase some of the gains Democrats have made in this year’s national redistricting process. The 2022 map had been poised to be balanced between the two major parties for the first time in generations, with a nearly equal number of House districts that are expected to lean Democratic and Republican for the first time in more than 50 years.
The map would also serve as a high-profile, if possibly temporary, victory for Mr. DeSantis, who has emerged as one of the Republican Party’s leading figures and has not ruled out challenging Mr. Trump for the party’s 2024 presidential nomination. The Florida House is expected to pass the map on Thursday and Mr. DeSantis is certain to sign it.
“I think they are good maps that will be able to be upheld,” said Joe Gruters, a Florida state senator who is the chairman of the state Republican Party.
If it is adopted into law, the Florida map will face legal challenges from Democrats, who clashed with Republicans on Tuesday over whether the proposal violated the state’s Constitution and the Voting Rights Act’s prohibition on racial gerrymandering.
“It does appear to be politically motivated and it does not take seriously the hard-working Black people in the state,” said Rosalind Osgood, a state senator from Broward County in South Florida.
Adam Kincaid, the executive director of the National Republican Redistricting Trust, the party’s main mapmaking organization, said that the proposed map complied with the state Constitution “while remaining faithful to the U.S. Constitution and the requirements of the Voting Rights Act.”
Some Democrats predicted that the DeSantis map would ultimately not pass legal muster — though any successful challenge would probably not arrive in time for the November elections. In addition to the Florida dispute, Democrats are locked in a court battle over a political gerrymander of their own in New York, where a judge last month invalidated Democratic-drawn maps.
This article will be updated.