He was elected in 1834 as a Whig anti-Jacksonian candidate to the Twenty-fourth Congress. He declined to be a candidate for renomination in 1836, serving 1835–1837. He resumed the practice of law.
Ingersoll was elected as a Whig to the Twenty-seventh Congress to fill the vacancy caused by the resignation of John Sergeant. He was reelected as a Whig to the Twenty-eighth, Twenty-ninth, and Thirtieth Congresses. He declined to accept the nomination as a candidate for reelection in 1848. In all, his second stay in office lasted from 1841 to 1849.
In 1852, President Millard Fillmore sent him to the United Kingdom as the U.S. Minister. He served about a year, and then retired to private life, devoting himself to literary pursuits. The degree of LL.D. was conferred on him by Lafayette and Bowdoin in 1836, and that of D.C.L. by Oxford in 1845.
He died in Philadelphia in 1868. Interment in St. Peter's Protestant Episcopal Churchyard.
Works
He was a warm adherent of the Union, and at the time of the American Civil War prepared an essay entitled "Secession, a Folly and a Crime." He published a translation from the Latin of Roceus's (Francesco Rocco's) tracts "De Navibus et Naulo" and "De Assecuratione" (Philadelphia, 1809), and was the author of a Memoir of Samuel Breck (1863).