Market Data 
It is not unprecedented for an incumbent president to abandon his reelection campaign. But it is rare, and no president has been pressured out of a reelection campaign out of concerns about his mental fitness.
One warning bell for Democrats who assume that a nominee younger than President Joe Biden would do better against former President Donald Trump: Republicans won the two most recent elections in which presidents eligible for reelection bowed out of their campaigns.
Democrats Harry S. Truman and Lyndon B. Johnson were succeeded by Republicans. A more immediate problem for Democrats is that if Biden were to drop out now – something he has so far shown no sign of doing – it would be the latest such decision in history.
Johnson and Truman left under pressure, handed the White House over to the other party
Comparisons between Biden and any of these presidents are not perfect. Neither Truman nor Johnson faced serious questions about their ability to do the job. Biden does.
Both Johnson and Truman, like Biden, were former lawmakers and former vice presidents. Unlike Biden, both had assumed the presidency after a death or assassination. Both Johnson and Truman then won the White House in their own right.
But both Johnson and Truman faced competition for their party’s nomination in 1952 and 1968 respectively. Both were embarrassed by a subpar showing in the New Hampshire primary, and both announced in the spring that they would not seek reelection.
Truman made the announcement that he would not be running during a speech in Washington that was broadcast nationwide, while Johnson made his announcement in a televised address from the White House.
Biden was never under any real pressure from Democrats to stand down earlier this year, and he faced only token opposition for the Democratic nomination. Nearly all of the delegates to the Democratic National Convention are pledged to him. In other words, Truman and Johnson both avoided a bruising primary by ending their reelection campaigns. Biden still has Democratic nomination sewn up, and he would have to choose to give it up.
Republicans, with help from their war hero nominee Dwight Eisenhower, won the White House, the Senate and the House in 1952, when Truman decided not to run again. Johnson’s decision not to run created a scramble for the Democratic nomination. Ultimately, Vice President Hubert Humphrey won the honor at the Democratic National Convention in Chicago. Humphrey would go on to lose the White House to Richard Nixon, but Democrats kept control of the House and the Senate.
Roosevelt and Coolidge left on high notes, and their party kept the White House
Theodore Roosevelt and Calvin Coolidge were Republicans who assumed the presidency after an assassination or death, and both chose to leave the presidency after serving one full term and most of another.
Roosevelt later regretted his pledge not to run again in 1908. He left office extremely popular and well respected and handed the White House off to his hand-picked successor, fellow Republican William Howard Taft. But Roosevelt was so aggravated by Taft’s performance and the direction of the GOP that he challenged Taft for the Republican nomination in the next presidential election. When Roosevelt could not get the nomination at the GOP convention, he ran as a third-party Progressive, or Bull Moose, candidate and beat Taft at the ballot box, although both lost to Democrat Woodrow Wilson.
Coolidge assumed the presidency when Warren G. Harding died of a heart attack in San Francisco. Coolidge then won the White House on his own. Never happy as president, he suffered loss during his time in office when his son died tragically after playing tennis at the White House. Coolidge also handed the presidency off to a fellow Republican, Herbert Hoover.
Coolidge disclosed his decision not to run on handwritten strips of paper given to reporters during his summer vacation the year before the election. The curt statement – “I do not choose to run for President in 1928” – caught everyone by surprise.
Despite an active and successful presidency, James K. Polk’s Democrats lost the White House after he stepped aside from the 1848 election. The Whig Party ran a war hero, Zachary Taylor, and former President Martin Van Buren ran as a third-party candidate. Taylor won, taking the White House from the Democrats.
James Buchanan promised in his inaugural address in 1857 that he would not run again. He said:
Buchanan, who was in office when Southern states protested Abraham Lincoln’s 1860 election victory by seceding, does not live in grateful memory of many historians. He’s viewed as one of the worst American presidents.
Democrats lost control of the White House and the Senate in 1860, and Lincoln became the first Republican president.
Rutherford B. Hayes, a Republican, promised to serve one term and did so after the disputed 1876 presidential election, by which a compromise handed Hayes the White House but also essentially ended Reconstruction.
Reforming the civil service was a major issue of the day, and it played into Hayes’ decision, according to his letter accepting the Republican nomination in 1876.
Republicans picked James Garfield at their 1880 convention to succeed Hayes, and Garfield not only won the White House but his party gained control of both the House and the Senate.
For Democrats today, holding on to at least one lever of power in Washington is a major priority as they fret over a possible second Trump term. If Biden becomes convinced that his own candidacy risks a Democratic wipeout, he might be swayed to step aside.
