The Founding Fathers didn't make it easy to impeach a president.

There's been much chatter about impeachment after it was revealed President Trump shared highly classified information to senior Russian officials at a White House meeting last month, putting a source on the Islamic State at risk.

Former FBI director James Comey testified Thursday, he believes Trump abruptly fired him to relieve pressure from the ongoing FBI investigation into possible collusion between Trump campaign associates and Russia in trying to influence the presidential election.

The U.S. president received criticism for pressuring Comey to shut down the agency's inquiry into former National Security Adviser, Michael Flynn, who was one of Trump's campaign associates.

"I hope you can let this go,'' Trump told Comey in the White House meeting.

A little background on impeachment

Only two presidents in U.S. history, Andrew Johnson and Bill Clinton, have ever been impeached, but both were acquitted of any convictions. Richard Nixon came close to being impeached but resigned instead.

In other words, no president has ever been impeached, convicted and removed from office in the history of the U.S.

According to the Constitution: Article II, Section 4, the President, Vice President and civil officers can all be impeached if convicted of treason or bribery. Those are the only two specific crimes named in the Constitution. Impeachment can also happen under "other high crimes and misdemeanors" but that is up Congress to determine.

The process of impeachment can take many months or even years to develop. The articles of impeachment, which are the charges against a public official, first need to be drafted, likely by the House Judiciary Committee or by an independent counsel.

The full House has the sole "Power of Impeachment", according to the Constitution. Each article of impeachment requires a simple majority vote. The Senate has the "sole Power to try all impeachments" while the U.S. Chief Justice presides.

A two-thirds vote is needed to convict. If convicted, a president or public official can be removed from office.

The process allows for a president to be impeached without actually being convicted of any crime. An official has the option of resigning, as Nixon did, without being impeached.

Is it likely Trump will be impeached?

"In theory, there is no reason why that couldn't happen," said Carlton Larson, a law professor at UC Davis and expert in American constitutional law.

While its true, anything is possible, there is one major advantage Trump has over other presidents who have faced impeachment.

"Republicans control the House," Larson explained.

In the past, Johnson, Nixon and Clinton all faced Congresses controlled by their political opposition so they had good reason to want the president out of office.

However, Trump is currently cushioned with a House that politically supports him. The majority of the House would have decide there's enough reason to draft articles of impeachment.

"Once they conclude Donald Trump does more harm than good, they'll drop him like a stone," Larson said. "I don't see that they're at that point."

However, Larson compared the Watergate scandal to Trump's current situation with the FBI investigation into Russia. Nixon was caught on tape telling the FBI not to investigate the Watergate scandal similar to how Trump asked Comey to let go of the Russia investigation.

If Nixon's situation was bad enough to call for impeachment, Trump's issues are not out of the question for impeachment.

"I do think if it got to that point, Trump would resign, sort of like Nixon did," Larson said.

It's important to note, Trump is not currently under investigation personally and according to Larson, the Russia case is harder to prove. Unless of course, some extremely damning evidence of presidential crimes came to light.