MINOT, N.D. — Only two United States Presidents have ever been impeached.

The House of Representatives impeached Democratic President Andrew Johnson in 1868 amid a squabble over the cabinet in the wake of President Abraham Lincoln's assassination.

About 130 years later the House impeached Democratic President Bill Clinton for lying under oath and obstructing justice during the investigation of the Monica Lewinsky affair.

The Senate convicted neither man.

Yes, both of them were Democrats. Before anyone on the right begins crowing about that, remember Republican President Richard Nixon was headed to impeachment, yes, but resigned before the ball could get rolling.

Also, Republican Warren Harding was likely saved from impeachment by death. The scandals uncovered once he was in the ground were certainly worthy of it.

Anyway, that's the total of Congress' exercise of its impeachment powers in the first 243 years of our nation.

I suspect, after the Trump era, impeachment is something that will happen more frequently, especially if President Trump gets impeached.

That's not a commentary on the case against Trump — I am not as confident as Sen. Kevin Cramer is that the President did nothing untoward in his dealings with Ukraine — but rather the cavalier way in which Democrats and their left-wing base have been talking about impeachment.

A progressive group, on inauguration day in 2017, set up an online petition calling for President Trump's impeachment. "From the moment he assumed the office, President Donald Trump has been in direct violation of the US Constitution," it claims.

Three weeks later a Democratic polling firm released a survey claiming some 46 percent of respondents support impeachment.

By March of 2017, Rep. Maxine Waters (D-CA) tweeted: "Get ready for impeachment."

Later that same month Berkeley, Calif., became (I believe) the first in a string of left-wing local governments to pass resolutions supporting impeachment.

Fast forward to the 2018 midterms, on her first day in office newly-elected Congresswoman Rashida Tlaib infamous said she was going to "impeach the mother****er."

The justification for most of this rhetoric was the Russia investigation, but that casus belli died earlier this year at the hands of one Robert Mueller.

Now the justification has shifted to the president's dealings with Ukraine.

If we agree, for the sake of argument, that the Democrats are right and the impeachment of Trump over that matter is right and proper, wouldn't their cause be helped if they hadn't been screeching about it since the day he took office?

Democrats have been so blatantly casual in their calls for impeachment that it's going to become a tactic, I'm afraid.

If Democrats can create a cloud over a Republican president by talking about impeachment from the first day of his term in office, GOP activists will think they can do it to the next Democratic president.

Trump may be impeached. He may even deserve to be impeached.

I think our nation would be better served if its leaders had been a bit more cautious about it.

Rob Port, founder of SayAnythingBlog.com, a North Dakota political blog, is a Forum Communications commentator. Listen to his Plain Talk Podcast and follow him on Twitter at @RobPort.