We smell a rat in Washington, and it reeks worse than the swamp that President Trump says he wants to drain.

In fact, the smell is emanating from the White House, where President Trump on Tuesday fired FBI Director James Comey, the man investigating the president’s ties to the Russian government and its efforts to sabotage the 2016 national election.

Mr. Comey’s firing is a clear signal of danger for American democracy and of a possible cover-up by President Trump.

In January, U.S. intelligence agencies concluded that Russian President Vladimir Putin ordered an effort to disrupt the U.S. presidential election to harm Democratic candidate Hillary Clinton and to boost the chances of winning for Mr. Trump, the Republican candidate.

In March testimony before a House intelligence committee, Mr. Comey confirmed an FBI probe into possible coordination between the Trump campaign and the Russian government to influence the election’s outcome. He also said he believed Russian meddling into U.S. affairs would continue because the Kremlin believed their efforts in the 2016 race had been successful.

On Tuesday, grand jury subpoenas were issued by federal prosecutors in the FBI probe just hours before President Trump fired Mr. Comey.

Coincidence?

We think not.

With growing evidence that Mr. Trump and his aides were working with the Russians to infect America’s democratic process, we believe President Trump’s latest actions are an attempt to quash the FBI probe by firing Mr. Comey and naming his replacement.

We have not been fans of Mr. Comey since the late 1990s, when he served as an assistant U.S. attorney in Richmond and targeted African-American men for lockup and to boost the prison rolls with his draconian “Weed and Seed” anti-violence program.

And we believe Mr. Comey recklessly and unfairly influenced the outcome of the presidential election by announcing 11 days before its end that he was reopening the investigation into Mrs. Clinton’s emails from a private server — though the probe turned up nothing untoward.

However, Mr. Comey’s firing by President Trump causes us even greater concern that the president is trying to undermine the U.S. government and our democracy.

The president’s stated reasons for firing Mr. Comey are flimsy at best, giving rise to feelings of déjà vu with the Watergate scandal of the 1970s involving President Richard Nixon’s involvement in a burglary at the Democratic National Committee’s headquarters and its cover-up.

When President Nixon was issued subpoenas for copies of White House tapes in the Watergate probe, he ordered the special prosecutor in the case to be fired. But the U.S. attorney general and his deputy at the time refused and resigned their posts instead. The third ranking justice department official at the time then complied with President Nixon’s order and fired the special prosecutor.

When the evidence mounted against President Nixon, he resigned. That was in August 1974.

Forty-three years later, history is repeating itself with President Trump seeking to damage the integrity and foundation of our democracy.

Aside from his book, “The Art of the Deal,” President Trump has shown us that he believes anyone and anything can be bought and sold. Last week, his son-in-law’s sister used her White House connection to try to persuade investors in China to pump money into a New Jersey housing development in exchange for U.S. visas and a path to citizenship.

We call on right-minded members of the U.S. Senate and House of Representatives and concerned people across the nation to stand up and say American democracy is not for sale. Nor are our elections.

And we add our voice to the loud and growing chorus of Democrats and Republicans calling for the appointment of an independent prosecutor or commission to look into possible collusion between President Trump and his campaign aides and associates and the Russians.

This is not going away, no matter how many times President Trump or his paid mouthpieces claim the allegations of collusion are fake and that there is “no there there.”

Let an independent special prosecutor get to the bottom of it. With Mr. Comey now perhaps able to testify more openly about what his probe has so far revealed, let the American people see if what they are smelling is more than the swamp.