Congress got its newest member when Republican John Curtis of Utah received the oath of office from House Speaker Paul Ryan.
His swearing in comes amid a full-court press by the GOP leadership to pass tax overhaul legislation by the end of the year.
Curtis was the mayor of Provo, Utah, when he was elected last week. His letter of resignation from the mayor's post took effect when he was sworn in.
He handily won a special election to replace Jason Chaffetz. He'll fill the final year of Chaffetz's term before facing re-election.
Curtis has signaled he intends to be a unifier in a deeply polarized Congress. To do that, he'll have to find the balance between supporting President Donald Trump and distancing himself from controversies surrounding the president.
