Sen. Darline Graham took the oath of office Tuesday to fill the vacancy left by the unexpected death of her older brother, four-term Republican Sen. Lindsey Graham. The late Graham died Saturday night at age of 71 of an aortic dissection, according to preliminary findings by the D.C. medical examiner. South Carolina Republican Gov. Henry McMaster announced Darline Graham’s appointment Monday, hours after President Donald Trump recommended her for the seat. “It is such an honor,” Darline Graham said at a press conference at the statehouse in Columbia. “Lindsey has always been there for me, and now I will be there for him.” While a number of widows have succeeded their late husbands in Congress, and brothers have previously succeeded siblings, Graham is the first sister to do so in U.S. history. She is also the first sibling to directly succeed a deceased senator and the first woman to serve in the Senate from South Carolina. Graham’s appointment can be seen as analogous to the existing model of widow succession, said Debbie Walsh, director of the Center for American Women and Politics at Rutgers University. “Lindsey Graham did not have a wife, and he even mentioned when he was running for president that he thought that his sister would kind of take over [the role of first lady] in many ways,” Walsh said. “So she actually seems to be taking over that role of spouse here.” Walsh pointed out that the real test for women in South Carolina politics will be who runs for the full term, with potential Republican contenders including Rep. Nancy Mace and Lt. Gov. Pamela Evette — although both women were unable to advance in last month’s gubernatorial primary. Graham said in a press conference Monday that she would work with her brother’s Senate staff to finish his work in office and help advance the president’s agenda. Her appointment also comes as questions linger around the prolonged absence of former Majority Leader Mitch McConnell of Kentucky. He issued a statement Sunday evening saying he was still recovering from a June 14 fall. McConnell confirmed he was recently moved to a rehabilitation center. Even with the addition of Graham to the ranks of Senate Republicans, McConnell's recovery means they still have one less vote ahead of a critical legislative work weeks before the August recess. Graham comes to Congress with years of working in state government jobs, but otherwise little political experience. She previously worked as a commissioner on the South Carolina Commission for the Blind and as communications and business services director for the South Carolina Vocational Rehabilitation Department. Graham and her brother were close: Lindsey Graham adopted Darline when he was 22 and she was 13, after both of their parents died in less than two years. “Lindsey was always my parent,” she told The New York Times when he was running in the 2016 presidential primary. His death has triggered significant shakeups in committees. Lindsey Graham was chairman of the Budget Committee, former chairman and second in line on the Judiciary Committee, had the president’s ear on foreign policy and was a senior member of the Appropriations and Environment and Public Works panels. “I’m still heartbroken over Lindsey, but I’m glad his sister is here,” said Senate Democratic Whip Richard J. Durbin, D-Ill. The two were part of the so-called “Gang of Eight” that came to a bipartisan compromise on a sweeping immigration overhaul in 2013 that passed the Senate but stalled in the House. Sen. Thom Tillis, R-N.C., said he was looking forward to getting to know Graham and was glad McMaster appointed her. “I think that was very fitting. I'm glad they did it that way because it took all of the politics out of the decision by doing that. So I think that was smart on the governor's part,” Tillis said. “And I'm sure that Darline will be great to work with if she's anything like her brother.” At the Monday press conference, Graham said her appointment to the Senate was a way to honor her brother’s memory before addressing her late brother directly. “I miss you more than I can even put into words,” Graham said. “But I’m gonna do this. I got it.” Nina Heller contributed to this report.