President Barack Obama served two terms in the White House and ended up being more popular than his predecessor, George W. Bush, at the time he left office, according to public opinion polls.

But Obama's popularity didn't mean he could have run for a third term, as some conspiracy theorists suggested. U.S. presidents have been limited to serving only two four-year terms in the White House since 1951 when the 22nd Amendment to the Constitution was ratified.

Obama's terms as president began on Jan. 20, 2009. He served his last day in office Jan. 20, 2017. He served eight years in the White House and was succeeded by Republican President Donald Trump.

Obama, like most ex-presidents, hit the speaking circuit after leaving office.

Third-Term Conspiracy Theory

Conservative critics of Obama began raising the prospect of a third term early in his tenure in the White House. Their motivation was to raise money for conservative candidates by way of scare tactics.

In fact, subscribers to one of former U.S. House Speaker Newt Gingrich's email newsletters were warned of a specific scenario that must have seemed rather frightening: President Barack Obama running for, and winning, a third term as president in 2016.

Conspiracy theorists believed the 22nd Amendment limiting presidents to two terms in office somehow would be wiped from the books by the time the 2016 campaign rolled around after Obama had won re-election to a second term in 2012.

That, of course, never happened. Trump pulled off an upset against Democrat Hillary Clinton.

Rumors About a Third Term

The email from Gingrich Marketplace, which is managed by the conservative group Human Events, claimed Obama would win a second term and then go on to win a third term that would begin in 2017 and last through 2020 despite the constitutional ban.

An advertiser to subscribers of the list wrote:

"The truth is, the next election has already been decided. Obama is going to win. It's nearly impossible to beat an incumbent president. What's actually at stake right now is whether or not he will have a third-term."

The advertiser's message was not written by Gingrich himself, who went on to run for the GOP nomination in 2012.

The email neglected to mention the 22nd Amendment, which reads in part: "No person shall be elected to the office of the President more than twice ..."

Notion of a Third Term in Wartime

Still, even some pundits writing in the mainstream media raised the question of whether Obama could serve a third term, depending on world events at the time a second term would expire.

Faheem Younus, a clinical associate professor at the University of Maryland and founder of the website Muslimerican.com, wrote in The Washington Post that attacking Iran could give Americans reason to keep Obama as president for a third term.

Younus made his case:

"Wartime presidents can sell a Double Whopper to a vegetarian. As the festinate decision of bombing Iran turns into a global conflict, don't expect our constitutional law professor turned president to decline his party's suggestion: if it can be ratified; it can be repealed. Repealing the 22nd Amendment—which some argue was never vetted publicly—is not unthinkable."

The notion of a third term was not unthinkable at one time. Before the ratification of the 22nd Amendment, Franklin Delano Roosevelt was elected to four terms in the White House—in 1932, 1936, 1940, and 1944. He is the only president to have served more than two terms.

Other Conspiracy Theories

Obama critics spread numerous conspiracy theories during his two terms in office: