Donald Trump is approaching his own Rubicon, it seems. The phrase "crossing the Rubicon" is a metaphor for crossing a line that, once crossed, cannot be uncrossed. "Burning your bridges" is a slightly-different metaphor with a similar meaning. For Trump, the Rubicon he is contemplating crossing is invoking the Insurrection Act to send in U.S. armed forces to an American city.

Once crossed, this will likely become a favorite response for Trump to any protests he doesn't like, which is why I see it as his Rubicon. The Act places not just total control but all decision-making in the hands of the president. He doesn't have to consult Congress or any governor or mayor, the president instead just decides on his own to send in the Marines (or Army or anyone else he feels like) to occupy American territory. Martial law may or may not be invoked in a de jure way, but it will be instituted in a de facto way no matter what. Soldiers armed with weapons of war will patrol the streets and decide what is allowable and what is not.

Of course, that's already taking place in Minneapolis to some extent. Thousands of ICE agents have swarmed the city wearing full warrior gear, armed with weapons of war, and hiding their faces behind masks. They are told they have full immunity for any of their actions, and their brutality and cruelty is not just seen as allowable by the president and his administration, it is actually being cheered on (and egged on) by them. The only immediately-identifiable difference in having the Army there too would be a slight difference in the uniforms, at least to people on the streets of Minneapolis.

The concept of sending in the troops to American cities should frighten anyone who believes in American democracy. Because once this Rubicon gets crossed, it could easily be replicated wherever Trump wishes. And he will be the one to define "insurrection" and "rebellion," so it won't be just people protesting ICE brutality, it could be people protesting anything Trump does. Or just going out to vote -- which is the scariest thing to contemplate about this frightening escalation.

In a recent interview, Trump was asked about the upcoming midterm elections, where Republicans are not in a good position (according to all the polls). Here's what he had to say about it:

In an interview with Reuters published Thursday, the president appeared to acknowledge that heavy losses loom -- but signaled political norms shouldn't apply to him.

"It's some deep psychological thing, but when you win the presidency, you don't win the midterms," Trump told the news agency, before boasting that he had achieved so much that "when you think of it, we shouldn't even have an election."

Later, when asked about this statement, Trump's press secretary brushed it all off as a joke:

The president was simply joking. He was saying, "We're doing such a great job, we're doing everything the American people thought, maybe we should just keep rolling." He was speaking facetiously.

This is the go-to explanation other Republicans have, whenever Trump says something completely outrageous. Remember when they all insisted that Trump was "just joking" about taking Greenland by force? These days, Denmark is decidedly not laughing at this "joke." Trump's obsessions about outrageous ideas sometimes cause them to actually happen.

Trump has already been in overdrive in the new year, as a Salon article just pointed out:

Two weeks into the new year, the Trump administration has already deposed a foreign leader, bombed several countries, threatened to invade several more, unleashed a secret police force on the city of Minneapolis -- killing one protester, shooting an immigrant in the leg and brutalizing many others -- and started a criminal investigation, based on bogus evidence, on the chair of the Federal Reserve. It's a lot.

That is a lot, and that list didn't even include the Department of Justice searching the home of a Washington Post reporter -- yet another chilling example of the use of governmental power to silence critics of the administration.

There was one other thing that happened recently that may be driving Trump's interest in the Insurrection Act. The Supreme Court ruled that the lower courts who had blocked Trump's deployments of National Guard forces to cities whose mayor and governor had not requested them were correct, and they allowed the rulings to stand. This forced Trump to back down in Chicago, Los Angeles, and Portland, Oregon. But his federalizing of the National Guard was done using a different law as justification. The Insurrection Act is a lot more clear-cut and gives the power of deciding when it is appropriate to use solely to the president. You can see why Trump is interested in it, since he thinks he should be able to do anything he wants without those pesky courts even having a say in the matter.

Less than ten months from now, America is supposed to have an election. All of the House and one-third of the Senate seats will be up for election. What is going to happen if we get to the end of the summer and the polls still show that Democrats are overwhelmingly favored to take back control of the House? What will Trump do, in that situation? Will he attempt to expand his definition of "insurrection" to the point of sending troops into cities and states led by Democrats, with the excuse of "keeping order"? Or will he just decide that the country is (as far as he is concerned) in a civil war, and therefore it would be impossible to hold elections?

These would not normally be serious questions -- normally they would be seen as too outlandish to even contemplate. But these are not normal times, and Donald Trump is not a normal president. Neither of those scenarios seem completely out of the question, at this point. And if Trump does cross the Rubicon and invoke the Insurrection Act in Minneapolis, they're going to seem a whole lot more possible.

In celebration of Wikipedia's 25th birthday, I will end today with an excerpt of their entry on the Rubicon's historical significance, which seems more than a little appropriate to point out:

In 49 BC, perhaps on 10 January, Julius Caesar led a single legion, Legio XIII Gemina, south over the Rubicon from Cisalpine Gaul to Italy to make his way to Rome. In doing so, he deliberately broke the law limiting his imperium, making armed conflict inevitable.... The presence of Caesar and his legion in Italy forced Pompey, the consuls, and a large part of the senate to flee Rome. Caesar's victory in the subsequent civil war ensured that he would never be punished for his actions.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant