The United States is in the midst of a constitutional crisis, and if we don’t act to resolve it now, we could see the end of the American experiment in democratic self-government.

That’s not something we heard on talk radio or read in an angry tweet.

That stark warning was made on the floor of the U.S. Senate this week by independent Maine Sen. Angus King, someone who, we have come to know, is careful with his words.

When he sounds an alarm like that, we listen.

King spoke Tuesday afternoon in favor of a new voting rights bill, the Freedom to Vote Act, of which he was a cosponsor.

The legislation is a scaled-back package that was negotiated after a more comprehensive bill, the For the People Act, could not clear a Republican filibuster. The Freedom to Vote Act met the same fate Wednesday, leaving sponsors with few options but promising to keep fighting.

Considering what King says is at stake, we hope that they do.

A constitutional crisis is a political conflict that can’t be resolved by the Constitution, either because it is silent or unclear on the specific issue or because the institutions in the system of checks and balances fail to do their jobs.

The crisis King describes comes from the false claims that Donald Trump won the 2020 election, a lie that has been echoed by Republican officeholders and, according to polls, is believed by one-third of all Americans and two-thirds of Republicans.

Republican-controlled state legislatures have passed “election integrity” laws that, if not stopped by federal intervention, would deny the opportunity to vote to tens of thousands of 2020 voters, many from the same minority groups that had to win their long fight for ballot access in 1965.

“One of our great political parties has embraced the idea that our last election was fraudulent, that our president is illegitimate, and that they must move legislatures across the country to ‘fix’ the results of future elections,” King said. “A substantial proportion of our population has lost faith in our democratic system and seems prepared to accept authoritarianism; all but the most extreme sources of information have been devalued, and violence bubbles just below the surface.”

King and the other supporters of the Freedom to Vote Act say what’s needed is a set of minimum standards that would guarantee that everyone who is qualified has the ability to vote, regardless of what state they live in. It calls for some of the features of Maine law to be available in every state, like Election Day registration and no-excuse absentee voting, and it would define what kinds of identification are acceptable in states that require ID for voting.

Failing to pass these reforms, King said, will allow Republicans in the states they control to tailor the electorate to their political needs. Then it will be Democrats who will say that the election results can’t be trusted and that the government is illegitimate.

As a consequence, King predicts,“we will be left with a downward spiral toward a hollow shell of democracy, where only raw power prevails and its peaceful transfer becomes a distant memory.”

Democracy is fragile, King told his colleagues, although they shouldn’t have needed the reminder. Just nine months earlier, many of them had to run for their safety when a mob stormed the Capitol to disrupt the certification of the presidential election, part of a plan to keep Trump in office.

Our imperfect system of self-government is based on the simple principle that all power comes from the people, who are regularly consulted in frequent elections. Destroying public faith in elections destroys the entire system.

King has sounded the alarm. Is anyone listening?