Democrat Mark Kelly was sworn into the U.S. Senate on Wednesday afternoon.

Democrat Mark Kelly was sworn into the U.S. Senate on Wednesday afternoon. / Getty Images

Updated at 2:55 p.m. ET

Former astronaut Mark Kelly was sworn in as the new U.S. senator from Arizona on Wednesday, after flipping the highly prized Senate seat for Democrats last month.

Vice President Pence officiated the ceremony, as is customary in his role as president of the Senate.

Kelly defeated Republican Martha McSally in November's special election, one of the most closely watched Election Day races, as Democrats had been attempting for years to push the state further blue. His swearing-in trims Republicans' Senate majority in the current term to 52-48.

Kelly, who brings experience in the military as well as NASA, was able to take his oath of office in December, as opposed to other incoming senators who will be sworn into office in January. Kelly's freshman term, ending in 2022, fills the remaining term of the late Republican Sen. John McCain, who died of brain cancer in 2018.

Kelly was accompanied by his wife, Gabby Giffords, a gun-safety advocate and former Democratic congresswoman from Arizona. Giffords served in the House until a 2011 assassination attempt caused her resignation the next year.

The Capitol chamber was filled with dozens of senators, many socially distanced, with a larger share of Democrats in attendance. Kelly was met on the floor with elbow bumps — which have replaced the traditional handshake as the favored mode of greeting during the pandemic — by Senate Majority Leader Mitch McConnell and many other members after the ceremony.

Kelly's twin brother, Scott Kelly, also a retired astronaut, watched the ceremony from the Senate chamber's public gallery. The gallery hasn't hosted guests for several months as a result of the pandemic.

"Awesome! A-plus!" Giffords said when asked for her reaction.

Scott Kelly said the moment was little surreal.

"Very exciting," he said, adding he had a good feeling this day was coming during the campaign. He added, "I've known him since my whole life. So definitely not something you ever expect. But, you know, I'm honored to have my brother now in the U.S. Senate."

Copyright 2020 NPR. To see more, visit https://www.npr.org.