Debbie Lesko, an Arizona Republican who withstood a Democratic onslaught in a heavily conservative congressional district, was sworn into the House Monday. She replaces GOP Rep. Trent Franks, who resigned in December after a former aide said Franks offered her $5 million to serve as surrogate mother to his child.

Lesko’s arrival in the House is expected to boost the ranks of the House Freedom Caucus, the hard-line group of conservatives who frequently frustrate GOP leaders’ legislative wishes. During her campaign, Lesko said, if elected, she would seek to join the group of roughly three dozen GOP lawmakers. She would be the second woman ever to join the group, which has been all-male since Rep. Cynthia M. Lummis (R-Wyo.) retired last year.

Two people familiar with the caucus’s workings said Lesko is unlikely to join the caucus at its meeting Monday, due to a scheduled appearance from White House adviser and presidential son-in-law Jared Kushner, but could join the group as soon as next week.

House Speaker Paul D. Ryan (R-Wis.) swore Lesko in Monday evening as she stood with fellow members of Arizona’s congressional delegation in the well of the House. In brief remarks, she thanked her family and constituents for their support.

Lesko arrives in Washington after winning an April 24 special election over Democratic nominee Hiral Tipirneni in Arizona’s 8th Congressional District, which encompasses Phoenix’s western suburbs, including the retiree haven of Sun City. But the narrower-than-expected margin of five points did little to allay Republican fears of a potential Democratic wave in the making, given that President Trump won the district by 21 points in 2016.

Lesko faces a rematch with Tipirneni in the fall for a full term in the 116th Congress, though national operatives in both parties see little chance of a different outcome. In a midterm election with all 435 seats at stake, the Arizona race is unlikely to attract the level of funding or press scrutiny seen ahead of last month’s special election.

Republicans are now preparing for another difficult special election to defend the House seat that was vacated earlier this year by Rep. Patrick J. Tiberi (R-Ohio) in a suburban Columbus district. While Ohio’s 12th Congressional District has an undeniable Republican lean, having voted for Trump by 11 points, it is clearly within reach for Democrats who closed much bigger gaps in special elections this year.

Voters in Ohio will select party nominees Tuesday ahead of the Aug. 7 special election there.