WASHINGTON — Republican women delivered critical victories to their party in the election, signaling the success of their efforts to recruit and elect a more diverse slate of candidates as they sought to counter Democrats’ huge advantage in adding women to their ranks in Congress.
Conservative women were nearing a historic level of representation in the House, more than doubling the number of female Republican incumbents in the chamber as they scored key upsets in battlegrounds across the country and beat back Democratic challengers flush with cash.
Republicans were celebrating their success at chipping away at Democrats’ House majority and feeling increasingly confident of maintaining control of the Senate. By Wednesday evening, they had elected 22 women and were on track to have the highest number of them serving in their congressional ranks, surpassing the previous record of 25 women elected in 2004.
Those wins came as Republicans fought to protect female incumbents in the Senate, where Joni Ernst of Iowa prevailed in her competitive race, Kelly Loeffler advanced to a runoff in Georgia, and Susan Collins won a decisive victory in her re-election race in Maine. Cynthia Lummis, a former House lawmaker, became the first Republican woman to represent Wyoming in the Senate, replacing the retiring incumbent, Senator Michael B. Enzi.
By Wednesday afternoon, Democrats had defeated only one Republican woman in the Senate, Martha McSally of Arizona, who had been expected to lose.
Republicans were still lagging far behind Democrats, who have spent years and huge sums to recruit and elect women across the country. But the Republican gains reflected the success of an urgent effort they undertook two years ago to make up for their widening deficit in enlisting women to run.
“In many ways, this cycle for the Republican women is a very simple story,” said Debbie Walsh, the director of the Center for American Women and Politics at Rutgers University. “You can’t see numeric gains in officeholders unless you have increases in number of candidates.”
But to reach gender parity in Congress, she cautioned, Republicans would have to continue prioritizing the recruitment of women in both chambers and not interpret their success on Tuesday as “a one and done.”
“These are important gains. They need to be celebrated; they need to be acknowledged,” Ms. Walsh said. “But women are still very underrepresented on the Republican side.”
The pickups were particularly remarkable in the House, where Democrats swept to power in 2018 by running a diverse class of contenders and sent a historic group of women into office. Just one new Republican woman, Representative Carol Miller of West Virginia, was elected to the chamber that year, raising alarms inside the party conference.
That set off a scramble by Republican leaders to steal a page from the Democratic recruiting playbook, eschewing the kind of candidates they had previously turned to — white, male, often veterans of politics — in favor of newcomers with diverse backgrounds.
“The Republican Party vowed to make gains among G.O.P. women, and it did because it prioritized the problem,” said Olivia Perez-Cubas, a spokeswoman for WFW Action Fund, a super PAC to elect conservative women that pumped millions of dollars into Republican primary races and the general election. “We’re seeing that Republican women will win.”
Republicans regained a number of seats they had lost in 2018, and partial returns showed women leading Democratic incumbents in other competitive districts, like in Staten Island, where Representative Max Rose of New York was fighting to hold off Nicole Malliotakis. Republican leaders said on Wednesday that they anticipated welcoming as many as 19 women to their ranks after a dozen candidates had notched decisive wins.
A woman won in nearly every district that Republicans had flipped by Wednesday, a striking statistic that bolstered the argument that conservative women could win competitive seats if they were able to make it through a primary to a general election.
Ashley Hinson, a former state legislator and television reporter, ousted Representative Abby Finkenauer of Iowa; Nancy Mace, the first woman to graduate from the Citadel, defeated Representative Joe Cunningham of South Carolina; and Yvette Herrell, a former state legislator and enrolled citizen of the Cherokee Nation, flipped Representative Xochitl Torres Small’s seat in New Mexico to become the first Native American Republican woman in Congress.
In Florida, Maria Elvira Salazar, a former broadcast journalist, stunned Democrats by defeating Representative Donna E. Shalala by a narrow margin in the state’s 27th Congressional District. And Michelle Fischbach, a former lieutenant governor, defeated Representative Collin C. Peterson of Minnesota, ending the tenure of the top Democrat on the House Agriculture Committee and a 30-year veteran of Congress.
Representative Kevin McCarthy of California, the minority leader, said in an interview on Wednesday that he and other party leaders had championed recruits like Ms. Hinson early in the cycle, recognizing that “women and minorities’ biggest challenge were primaries, not general election.” More than 200 Republican women ran for the House this cycle.
“They’re not going to give up,” Mr. McCarthy said. “These are the type of people you see who are just natural leaders. They’re not being elected because they’re a woman, but they’re going to break barriers where they haven’t been able to get there before.”
Republicans were also optimistic on Wednesday about the chance of victories by Young Kim, the first Korean-American Republican woman elected to the California Legislature, and Michelle Steel, a first-generation Korean-American and member of the Orange County board of supervisors, who were challenging Democratic incumbents in tight races in California.
Democrats, for their part, added to the diversity of their ranks with victories by Cori Bush, the first Black woman elected to represent Missouri in Congress, and Ritchie Torres and Mondaire Jones, both New York Democrats who became the first openly gay Black men to be elected to Congress. Mr. Torres is also the first openly gay Afro-Latino elected to Congress.