Being more interested in politics than law, Blair came back to St. Louis in the summer of 1847. A personal and political friend of
Thomas Hart Benton, he became known for his views opposing
slavery and strong advocacy of free soil politics, though he was a slaveholder himself. Blair served in the
Missouri House of Representatives from 1852 to 1856, when he was elected to Congress. Missouri and the nation were in the midst of a sweeping
political realignment which left Blair's partisan identity uncertain. According to the March 24, 1857 issue of
The Western Democrat, a newspaper from
Charlotte, North Carolina, Blair was elected as a Democrat and was "generally classed with the
Opposition" due to his views on slavery. Other sources from this period refer to Blair as a "Free Democrat" and an "anti-Administration Democratic candidate ... of the
Douglas and
Wise stamp." The
Biographical Directory of the United States Congress states he was seated as a Republican in the
United States House of Representatives. Blair was an outspoken supporter of the
Wilmot Proviso and opposed the proslavery
Lecompton Constitution for the
Kansas Territory. On January 14, 1858, he delivered a major speech describing slavery as a national problem, proposing to solve it by both gradual emancipation and the settling of freed slaves in
Latin and
Central America. A year later in Boston, he gained national prominence with his speech,
The Destiny of the Races of This Continent. Towards the end of his first term, Blair was defeated in his bid for re-election in 1858 by
John R. Barret. He went on to successfully contest the results and was finally seated in the
36th Congress on June 8, 1860. However, he resigned just seventeen days later on June 25, then lost his bid in the subsequent special election, the seat instead being refilled by Barret on December 3. In the regular election of 1860, he was subsequently re-elected to the
37th Congress, serving in it as chairman of the important
Military Affairs Committee. He again resigned in July 1861 in order to become a colonel in the
Union Army. In 1862, he won election to the
38th Congress but in a reversal of fortune was himself forced to relinquish his seat on June 10, 1864, after his opponent,
Samuel Knox, successfully contested the results. The Blairs were unwavering supporters of
Abraham Lincoln during his rise to the presidency and years in office and in return enjoyed his political patronage. In December 1863, Lincoln said, "The Blairs have to an unusual degree the spirit of clan. Their family is a close corporation. Frank is their hope and pride. They have a way of going with a rush for anything they undertake, especially have
Montgomery and the Old Gentleman." In the days following Lincoln's election as president, when it became evident that several Southern states were advocating
secession, Blair was among the leaders of the
Unionist political movement in Missouri which advocated the use of its paramilitary
Home Guard, if necessary, to prevent Missouri from seceding. In time, Blair became alienated from Radical Unionists like
B. Gratz Brown who favored the
immediate emancipation of all enslaved people in Missouri, instead favoring Lincoln's proposal for gradual emancipation. Brown emerged as the leader of the Radical Union Party in Missouri, while Blair's faction became known as the Conservative Party. ==Civil War==