Washington (CNN) - Democrat Mark Critz was sworn in Thursday as a member of the House of Representatives.
Critz won a special House election Tuesday to fill a vacant seat in Pennsylvania's 12th Congressional district after topping Republican Tim Burns by double digits in the battle to succeed the late Democratic Rep. Jack Murtha.
Critz was a longtime aide to Murtha, who represented the district for 18 terms until he passed away from complications following gallbladder surgery this year.
"This moment is bittersweet for me because I wouldn't be here right now if Jack Murtha hadn't left us too soon," Critz told lawmakers, after being sworn in on the floor of the House.
With Critz now a member of Congress, the Democrats hold a 255 to 177 advantage in the House, with three seats currently vacant. The number of vacancies should rise to four Friday, when Republican Rep. Mark Souder of Indiana is expected to resign. Souder abruptly announced his resignation Tuesday, after acknowledging that he "sinned against God" by engaging in a relationship with a member of his staff. The 59-year-old married father of three, who just won a competitive primary, said he will leave office at the end of the week.
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