In June 1864, the Republicans and War Democrats joined to form the National Union Party. Although Lincoln was renominated, War Democrat Andrew Johnson of Tennessee was named to replace Hamlin as Lincoln's running mate. Lincoln was seeking to broaden his base of support and was also looking ahead to Southern Reconstruction, at which Johnson had proven himself adept as military governor of occupied Tennessee. Hamlin, by contrast, was an ally of the Northern "Radical Republicans" (who would later impeach Johnson). Lincoln and Johnson were elected in November 1864, and Hamlin's term expired on March 4, 1865.