Born April 24, 1811, at Washington County, Pennsylvania, near Wheeling, Virginia. He attended private schools and was graduated from Washington College, Washington, Pennsylvania, and from the law department of Jefferson College, Canonsburg, Pennsylvania, in 1833. Mr. Leffler was admitted to the bar and commenced practice in Wheeling. He moved to Burlington, Iowa (then a part of Michigan Territory), in 1835. He served in the Territorial Council 1841 through 1846. He filled a vacancy in the Fourth Legislative Assembly, and served two consecutive two-year terms in the Fifth through the Eight Legislative Assemblies. Mr. Leffler was a member of the constitutional conventions in 1844 and 1846. He served as permanent president during the first convention and upon the admission of Iowa as a State into the Union was elected as a Democrat to the Twenty-ninth Congress in 1846. He was reelected to the Thirtieth and Thirty-first Congresses and served from December 28, 1846, to March 3, 1851. He was chairman of the Committee on Invalid Pensions (Thirty-first Congress). He was engaged in the practice of his profession and in agricultural pursuits in Burlington, and an unsuccessful candidate for election in 1856 to the Thirty-fifth Congress and unsuccessful Democratic candidate for Governor of Iowa in 1875. Mr. Leffler died at his home, near Burlington, Des Moines County, Iowa, September 7, 1879, and was interred in Aspen Grove Cemetery.