Benjamin Franklin Wade was a “radical Republican” and served as president pro tempore of the U.S. Senate in 1868, when President Andrew Johnson was brought up on impeachment charges. Wade had been critical of Abraham Lincoln’s actions during the Civil War, and had even more of a dislike for Johnson, who succeeded Lincoln after the latter was assassinated. Congress was trying to strong-arm Johnson into changing the way Reconstruction was behing handled, and Wade led the charge. When Johnson moved up to President, a new Vice President was not selected, so Wade was next in line for the office of President. (In 1886, the Speaker of the House was moved into this “number three” spot.)
By a 5-4 vote in late 1867, a committee of the House of Representatives passed the resolution of impeachment against Johnson, leading to a trial the next spring. A full two-thirds vote of the Senate was required to impeach Johnson, but the final tally was one vote short. Many at the time believed that Johnson was only acquitted because (1) he had only one year left in his presidency, and (2) many Senators didn’t like the idea of Wade becoming president, including a few of his supporters. Wade and his followers had been so vocally critical of the presidency, it didn’t seem “appropriate” for them to vote him into that position.
Only one vote from the presidency, Wade never made it any further in politics. When Ulysses S. Grant was named the next Republican presidential candidate, his suggestion of Wade as his running mate was rejected by his party.