Trump refused to unveil Obama's White House portrait after the former president criticized his handling of the COVID-19 outbreak. Here are 8 other famous presidential feuds in history.

Founding Fathers John Adams and Thomas Jefferson had a tumultuous off-and-on friendship before both died within hours of each other on July 4, 1826, according to CNN.

Their friendship was first tested when the nation's first president, George Washington, decided not to seek a third term, and the two ran against each other.

Adams won that election, but things turned sour when Jefferson challenged him again four years later.

Supporters for Jefferson called Adams a "hideous hermaphroditical character," while Adam's supporters called Jefferson "a mean-spirited, low-lived fellow."

Adams was so angered at losing to Jefferson in this race that he left town early and skipped Jefferson's inauguration.

However, the two did reconcile somewhat about a decade later, when they started exchanging letters again.

Historians consider the 1828 presidential election to be one of the nastiest in US history, according to CNN.

The reasons for this date back to the previous election, in 1824, which was also between John Quincy Adams and Andrew Jackson.

Adams won, and many felt that Jackson had been robbed of victory because of a deal that Adams cut with another contender, Henry Clay, whom he later made his secretary of state.

Adams and Jackson were also extremely different men.

Adams was the son of the nation's second president, came from a prominent New England family, was Harvard educated, and had spent a good portion of his life abroad.

Jackson, meanwhile, had a tough upbringing, during which he was kidnapped and beaten by British soldiers, orphaned, and largely had to fend for himself in South Carolina.

During the 1828 election, Adams was called a pimp, while Jackson's wife was labeled a slut.

According to The Atlantic, when Jackson eventually won, his supporters stormed the White House and Adams had to secretively escape.

While Civil War hero Ulysses S. Grant was a member of Andrew Johnson's Democrat party earlier in his life, he switched sides after Johnson became president following Abraham Lincoln's assassination.

Grant and Johnson disliked each other so much that Grant refused to ride to his inauguration with Johnson in his carriage, as was the custom at the time, according to The Atlantic.

As a result, Johnson refused to go to the ceremony and stayed at the White House.

The 1932 election was an extremely fraught battle between Republican President Herbert Hoover and his Democratic challenger, Franklin D. Roosevelt, as they argued over the best ways to lift the country out of the Great Depression.

During the election, the men launched personal attacks against each other, with Hoover calling Roosevelt a "chameleon on plaid" and Roosevelt calling Hoover a "fat, timid capon," according to The Atlantic.

President Harry S. Truman and Gen. Dwight D. Eisenhower had a friendly relationship until the latter decided to run for president in 1952.

Truman, who was supporting the Democratic nominee in the election, Adlai Stevenson, started to criticize Eisenhower, who was running on the Republican ticket.

Among the jabs he threw at Eisenhower was an accusation that he didn't protect Gen. George Marshall from attacks by Sen. Joseph McCarthy, according to an article by an archivist at the Truman presidential museum.

McCarthy's allegations of treason against Marshall put Eisenhower in a tough spot since McCarthy was a Republican and Marshall was one of his mentors.

Eisenhower initially planned to condemn McCarthy and publicly support Marshall in a speech on the campaign trail in McCarthy's home state of Wisconsin, but eventually decided against it, according to PBS.

Nevertheless, he didn't like being criticized for it by Truman.

"Eisenhower, a relative newcomer to presidential politics, took Truman's campaign attacks personally and was bitter about them for years," Truman archivist Samuel W. Rushay Jr. wrote.

While Lyndon B. Johnson was John F. Kennedy's vice president, the two weren't exactly best friends.

For one, Johnson did not approve of Kennedy's appointment of his brother Bobby as Attorney General. Johnson called Bobby Kennedy a "snot-nosed little son of a b----," according to Politico.

In fact, when he became president after Kennedy's 1963 assassination, Johnson signed an anti-nepotism law making sure it wouldn't happen again.

Johnson also did not like the limited power he was given in Kennedy's administration.

In a later interview Johnson said that his private meetings with the president were extremely awkward.

''Every time I came into John Kennedy's presence. I felt like a goddamn raven hovering over his shoulder," he said, according to The New York Times.

President Lyndon B. Johnson became furious with Richard Nixon after he found evidence that the then-Republican presidential nominee was trying to sabotage the Vietnam War peace talks.

Over the years it was revealed that Nixon had a representative convince the South Vietnamese to drop out of the peace talks, with the promise that they would get a much better deal under Nixon.

Nixon was afraid that if peace was brokered under Johnson, then his vice president Hubert Humphrey would win the election.

In tapes that were later declassified, Johnson said Nixon was guilty of treason and had "blood on his hands."

Democratic President Jimmy Carter's time in office was cut short when Republican candidate Ronald Reagan beat him in the 1980 election, making Carter a one-term president.

The transition between administrations was not a happy one.

According to The New York Times, at a White House meeting about the transition, Carter got upset with Reagan for reportedly not paying enough attention or taking notes.

It was also reported that Nancy Reagan asked if the Carters could move into Blair House — the president's guest house — a few weeks before the Inauguration so that the Reagans could get a head start on redecorating the White House.

Blair House is usually where incoming presidents stay on the night before their inauguration.