(CNN) When Michael Flynn quit under pressure as national security adviser, he became the second high-ranking official in Donald Trump's inner circle to step down over investigations of the campaign's alleged ties to Russia.

In classic Washington fashion, some dubbed the scandal "Russiagate," harking back to the epochal Watergate scandal that ousted a president in 1974, but it's far too early to know how this scandal will rank compared to the presidential scandals of recent decades.

The White House portrayed Flynn's ouster as a result of his denying to Vice President Mike Pence that he had discussed sanctions in a phone call with the Russian ambassador when, in fact, he had. After he resigned, CNN and The New York Times broke stories detailing frequent contact between the Trump campaign and the Russians.

President Trump, along with many other Republicans who support him, has taken a page out of President Richard Nixon's playbook by attempting to focus the story on who is leaking the information. Rather than denying any of the stories, they are instead talking about the threat to democracy that they say comes from the leaks.

Trump has gone after former President Obama, saying he was weak against Russia, and he continues to lash out against what he called the "fake news" media for their "conspiracy theories and blind hatred," as he said in a tweet. Trump and Reince Priebus have denied the reports of contacts with Russia, though outside the circle of Trump supporters, many people are not buying their denials.

The million-dollar question is now, what happens to this presidency next?

There are growing demands for a congressional investigation into these kinds of questions: What were President Trump's advisers talking about with the Russians and what did they say with regard to the sanctions? How involved was President Trump, if at all, in these communications now and in the campaign? Were there connections between the interaction and the extensive hacking that took place by the Russians to influence the outcome of the election? What are President Trump's business interests in Eastern Europe?

It may be too facile to compare it to Watergate given what we know so far. Indeed, history shows that presidential scandals can move in very different directions.

Lance-gate

There are many scandals that seem big for a moment but quickly fizzle. President Jimmy Carter confronted a scandal involving his longtime adviser Bert Lance, the former president of the Calhoun First National Bank of Georgia, who served as the director of the Office of Management and Budget.

Questions emerged about Lance's financial holdings and transactions. The media called it "Lance-gate." As more revelations emerged, Lance resigned. The scandal hurt Carter's approval ratings but it also went away. In this case, there was no evidence of serious wrongdoing and the presidency moved on to other issues.

A number of the scandals that President Bill Clinton faced, including Whitewater and "Travel-gate," also turned out to be overblown -- and fizzled.

Lewinsky

There are presidential scandals that are not devastating in themselves but open the door to something more damaging. Clinton was impeached by the House of Representatives in 1998 as a result of his having lied about his sexual relationship with White House intern Monica Lewinsky.

The partisan forces pushing for an investigation were extremely strong, and independent counsel Kenneth Starr's investigation into charges of sexual harassment against Paula Jones opened the door into another room that gave Republicans the fodder they needed to go on the attack.

While the House did impeach the president, the Senate voted not to convict. The public was with Clinton, convinced that Republicans had overreached, and Clinton's foes were the ones who suffered the most political damage.

Iran-Contra

Some scandals with clear evidence of wrongdoing bring down officials in the White House -- without direct risk to the president himself. Watergate spawned the phrase, "What did the president know and when did he know it?" -- and that has become a question that often determines how much damage a scandal can cause a president.

The Iran-Contra scandal revealed that Ronald Reagan's administration had been secretly selling weapons to Iran, and National Security Council officials used the proceeds to fund the Nicaraguan Contras despite a congressional prohibition against doing so.

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The scandal was enormous, resulting in Reagan suffering the worst fall in approval ratings since those numbers were tracked and leaving the White House paralyzed as it struggled to survive. While many high-level officials were convicted in court for their actions, Reagan was not personally affected.

Not only did Reagan stay in office -- he ended his two-term presidency with a historic diplomatic breakthrough as he signed a major arms agreement with the Soviet Union.

Iran-Contra did not bring Reagan down, in large part because there was no smoking gun to prove that Reagan knew money was being diverted to the Contras.

Politically, the administration was able to turn the congressional investigation in their favor. When Lt. Oliver North, the point man in the operation at the National Security Council, testified, many Americans loved his patriotic appeal and his claim to have done what was best for his country. Most Republicans rallied to Reagan's side.

Watergate

Then there are the big scandals like Watergate that have the potential to bring down a president. The scandal started with evidence Nixon's reelection campaign had been involved in a break-in at the Democratic headquarters at the Watergate complex.

The president then was thin-skinned and paranoid, lashing out at every part of the establishment which, in his mind, was stacked against him. The scandal kept getting bigger and bigger until there was clear evidence that Nixon had tried to obstruct the investigation.

The journalistic community, led by The Washington Post, was fully mobilized to find out what happened and produced some of the most-hard hitting coverage that Americans had ever seen. Not only did Democrats then control the Congress and lead the charge against Nixon, but a significant number of Republicans, including Barry Goldwater, told him it was time to resign.

In that case, the evidence and the scandal resulted in his presidency coming to a dramatic end in August 1974. As the comedian Louis CK says in a bit on the subject, "We saw the president of America cry and then quit being the president. That s--- was crazy!"

New scandal environment?

It is too early to tell in which direction this unfolding scandal will head. If there is clear evidence of a direct connection between the Trump campaign, or Trump's personal economic interests, and the Russian cyber-intervention into the election, this could get worse than Watergate, becoming a trauma for the nation.

But Trump can survive this. If there is no evidence that he was directly involved in these communications, the public might be forgiving. And partisanship plays to his advantage. If most congressional Republicans hold the line against any serious investigation, Democrats will be stymied.

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While Washington focuses on this scandal, the administration has been moving ahead with some pretty big initiatives -- including deregulating huge swaths of the economy -- that bring Republicans great delight. Trump's opponents might want to note that his job approval has remained strong among his supporters.

As The New York Times reported, Americans are following this scandal through a divided media . The conservative press has focused on the leaks, not the Trump team contacts with Russia, and it is possible that a critical part of the electorate understands the story through a sympathetic lens.

In other words, there might no longer be a common national media platform through which today's "Woodward and Bernstein" can have maximum impact with their reporting on this story.

Trump could survive the scandal while Democrats get consumed with it, taking their eye off the ball and letting the Trump administration hand Republicans big wins that shore up his political standing. Trump's ability to distract the press and perpetually shift the conversation might prevent the kind of sustained journalistic focus that broke Watergate.

One thing is for sure—the whole world is watching, and President Trump is facing a test unlike anything that he has confronted before.