ALSO SEE: Supreme Court, With No Dissents, Rejects GOP Challenge to California's New Election Map

The state’s Republican Party had asked the justices to step in and block the new congressional maps, which give an advantage to Democrats, before the midterms.

The Supreme Court on Wednesday cleared the way for California to use a new congressional map designed to help Democrats for the midterm elections.

The justices rejected an emergency request by the California Republican Party to override a federal court and block the map before the November vote. The decision is a victory for Democrats, who had devised the plan after President Trump pushed Republican-led states to redraw their maps to help the G.O.P. pick up seats in the election.

The unsigned order did not include a vote count or the court’s reasoning, which is typical in such emergency decisions.

“Donald Trump said he was ‘entitled’ to five more congressional seats in Texas,” Gov. Gavin Newsom of California said in a statement on Wednesday. “He started this redistricting war. He lost, and he’ll lose again in November.”

The dispute is the latest challenge to a state congressional map to come before the justices in recent months.

In December, the Supreme Court cleared the way for Texas to use its new congressional voting map for the midterm elections. Texas Republican leaders had asked the court to weigh in after a divided panel of federal judges had temporarily blocked the map, which was designed to help the G.O.P. potentially pick up seats.

In a concurring opinion in the Texas case, Justice Samuel A. Alito Jr. nodded to efforts to gain a partisan advantage by both parties before the midterms, writing that it was “indisputable” that “the impetus for the adoption of the Texas map (like the map subsequently adopted in California) was partisan advantage pure and simple.” Courts have said it is legal to gerrymander based on party politics as opposed to race.

An attorney for the California Republican Party said the party will continue to fight its underlying case in the lower court even though it did not win the emergency injunction it sought to block the new maps this year.

“The Federal District Court applied a standard that would permit any state to use a racially gerrymandered election district map if the voters approved the map without knowing what their officials had done,” according to a statement from Michael Columbo, an attorney representing the California Republican Party. “This is a novel interpretation of the law that we believe is incorrect and dangerous.”

The fight over redistricting began in the summer, when Mr. Trump pushed Gov. Greg Abbott of Texas to redraw the state’s congressional districts to add Republican seats in hopes of maintaining control of the House of Representatives.

California lawmakers quickly responded with a redistricting effort of their own. In August, Mr. Newsom signed two redistricting bills and declared a special election to ask the state’s voters to approve the new voting map, which could help Democrats flip five seats and bolster four swing seats with more Democratic-leaning voters.

Hours after the state’s voters overwhelmingly approved the plan in November, leaders of the California Republican Party sued. A divided three-judge panel in federal court in Los Angeles upheld the map.

A district judge, Josephine Staton, writing for the majority, said the evidence showed that the state’s new map “was exactly what it was billed as: a political gerrymander designed to flip five Republican-held seats to the Democrats.”

The California Republican Party quickly appealed to the Supreme Court. In a brief to the justices, the challengers argued that “under the guise of partisan line-drawing,” California “expressly used race” in drawing up its map, a “pernicious and unconstitutional” action.

Lawyers for the Trump administration weighed in with a brief supporting the state Republican Party. Solicitor General D. John Sauer asserted that the justices should treat California’s map as different from the Texas map because California’s map was “tainted by an unconstitutional racial gerrymander.” Mr. Sauer argued that the state’s new district boundaries had been drawn to bolster Latino voters.

In response to the emergency application, Mr. Newsom and Secretary of State Shirley Weber, both Democrats, denied that the map had been drawn to give an advantage to Latinos. They pointed out that the number of Latino-majority districts in the state remained unchanged under the new map.

The state leaders said in their brief that it would be “strange” for California to redistrict to help Latino voters and then adopt a map with the same number of majority-Latino districts.

They urged the justices not to block the state’s map “on a hurried timetable with limited briefing, where the requested relief would nullify the choice of millions of voters and displace state election laws in the middle of an active primary campaign.”

The order served as a reminder that the justices have yet to rule on a broader challenge to how states draw legislative districts. Earlier in the term, they heard argument in a major challenge to Louisiana’s voting map, weighing whether lawmakers’ use of race as a factor in drafting the state’s congressional map violated the Constitution.

Through their lawyers, the plaintiffs in that case — a group of white Louisiana voters who had challenged the map — weighed in with a brief to ask the justices to temporarily block the California map. They claimed that it, too, was an illegal racial gerrymander and urged the court to act, even with an election looming.