 Complete the following phrase:  Incumbent president Andrew Johnson had succeeded to the presidency in 1865 following the assassination of Abraham Lincoln, a Republican. Johnson, a War Democrat from Tennessee, had served as Lincolns running mate in 1864 on the National Union ticket, which was designed to attract Republicans and War Democrats. Upon accession to office, Johnson clashed with the Republican Congress over Reconstruction policies and was impeached and nearly removed from office. Johnson received some support for another term at the 1868 Democratic National Convention, but, after several ballots, the convention nominated Seymour, who had formerly served as Governor of New York. The 