[40] He won a second term in 1845 against William G. Brownlow, presenting himself as the defender of the poor against the aristocracy. In his second term, Johnson supported the Polk administration's decision to fight the Mexican War, seen by some Northerners as an attempt to gain territory to expand slavery westward, and opposed the Wilmot Proviso, a proposal to ban slavery in any territory gained from Mexico. He introduced for the first time his Homestead Bill, to grant 160 acres (65 ha) to people willing to settle the land and gain title to it.[41][42] This issue was especially important to Johnson because of his own humble beginnings.[41][43]
In the presidential election of 1848, the Democrats split over the slavery issue, and abolitionists formed the Free Soil Party, with former president Van Buren as their nominee. Johnson supported the Democratic candidate, former Michigan senator Lewis Cass. With the party split, Whig nominee General Zachary Taylor was easily victorious, and carried Tennessee.[44] Johnson's relations with Polk remained poor; the President recorded of his final New Year's reception in 1849 that

.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 40px}.mw-parser-output .templatequote .templatequotecite{line-height:1.5em;text-align:left;padding-left:1.6em;margin-top:0}Among the visitors I observed in the crowd today was Hon. 