Dalzell was a delegate to the Republican National Conventions in 1904 and 1908, and served as a Regent of the Smithsonian Institution from 1906 to 1913. After the death of Pennsylvania representative Henry H. Bingham in March 1912, Dalzell became the longest continuously-serving member of the House of Representatives, or the "Father of the House." He was defeated for renomination later in 1912 and left Congress in March 1913.