If Trump Is Impeached, Who Becomes President? How the White House Succession Plan Works​

Amid the continuing investigations into Russian meddling in the 2016 presidential election, some rank-and-file Democrats and American citizens have discussed the idea of the 45th commander in chief not completing his full term in office.

Related: President Trump impeachment process set to begin

If Trump dies, resigns or is removed from office in the next four years, Vice President Mike Pence would replace him in the White House. President John Adams, who was also a two-term vice president, told his wife the position below the commander in chief is "the most insignificant office that ever the invention of man contrived or his imagination conceived." But throughout history, nine vice presidents have carried out the remainder of a presidential term because of a sitting leader's death or resignation. Four of those men were later elected to a full term. The first was John Tyler in 1842, after William Harrison died of pneumonia; the most recent was Gerald Ford in 1974, when Richard Nixon resigned. Spiro Agnew is the only vice president to resign, under Nixon in 1973.

President Donald Trump arrives next to Vice President Mike Pence to announce his decision that the United States will withdraw from the landmark Paris Climate Agreement, in the Rose Garden of the White House, on June 1. If something happens to Trump, Pence is next in line to become president of the U.S. Kevin Lamarque/Reuters

Pence is generally well-liked in Republican circles, and, as a staunch conservative, is viewed by some established party members as a calming presence for those who don't like what they see in the president. The former Indiana governor, now 58, who has described himself as "a Christian, a conservative and a Republican—in that order," was an early believer in the Tea Party movement and led congressional Republicans' crusade to defund Planned Parenthood. In 2015, he signed a controversial religious freedom bill into law, and a year later, he signed one of the most restrictive abortion laws in the country, a measure that blocks mothers from seeking the procedure due to objections to the fetus's gender or race, or because the baby would be born disabled.

But what happens if neither the president nor the vice president can hold office? The answer has changed throughout U.S. history.

History of the Presidential Succession

U.S. laws about succession were first created in 1792. The first measure placed the Senate president pro tempore and speaker of the House in the line of succession. But in 1886, Congress replaced the two congressional officials with Cabinet officers in order of their agencies' creation. Ultimately, in 1947, President Harry Truman signed the Presidential Succession Act that reinserted those officials behind the vice president, but placed the speaker of the House ahead of the president pro tempore.

Under the current Trump administration and after Pence, next would be House Speaker Paul Ryan, then the president pro tempore of the Senate, Senator Orrin Hatch (R-Utah). From there, the list follows 15 Cabinet-level departments, first with Secretary of State Rex Tillerson and last with Secretary of Homeland Security John Kelly. The Cabinet's role is to advise the president on any subject he may require relating to the duties of each member's respective office.

In U.S. history, the line of succession has never gone beyond the vice president.

What's Happening With Trump?

Republicans have mostly rallied behind Trump, despite his firing last month of former FBI Director James Comey, and an accusation he shared sensitive national security information with Russian officials. Comey testified Thursday in front of the Senate Intelligence Committee on Capitol Hill into alleged Russian meddling in the 2016 presidential election.

Meanwhile, a Texas Democrat, Representative Al Green, on Wednesday took the first legislative step toward removing Trump from office, by submitting drafts of his articles of impeachment. He first officially called for Trump's impeachment during a fiery speech on the House floor last month.

But top Democratic leaders have urged party members not to discuss impeachment until ongoing investigations into the Trump administration are completed.

What's the History of Impeachment in the U.S.?

Andrew Johnson and Bill Clinton are the only two U.S. presidents impeached by the House, in 1868 and 1998, respectively. Later, both were acquitted at trials held by the Senate.