On Wednesday, former Illinois Rep. Joe Walsh trended nationally on Twitter after he tweeted, "On November 8th, I'm voting for [Republican presidential candidate Donald] Trump. On November 9th, if Trump loses, I'm grabbing my musket. You in?" After being thrust into the media spotlight, Walsh quickly tried to walk his statement back, claiming that he was simply calling for nonviolent acts of "civil disobedience." But given Walsh's history of threatening political rhetoric, few were buying it. The meaning was clear. He was calling on his 78,000 Twitter followers to engage in armed rebellion should Democratic presidential candidate Hillary Clinton win the election.

It seems likely that Walsh was inspired by Donald Trump himself when he composed his tweet. The Republican standard-bearer has made it clear that he will not accept the results of the presidential election unless he wins. He has also repeatedly endorsed the use of political violence, thereby creating an existential threat to our democracy the likes of which we haven't seen since the Civil War. At a rally in August, Trump told supporters, "If [Clinton] gets to pick her judges [for the Supreme Court], nothing you can do, folks. Although the Second Amendment people – maybe there is, I don't know." Connecticut Sen. Chris Murphy's response was accurate and chilling: "This isn't play," he tweeted at Trump. "Unstable people with powerful guns and an unhinged hatred for Hillary are listening to you."

The American people would seem to agree. A recent USA Today/Suffolk University poll found that 51 percent are concerned about the possibility of violence on Election Day or afterwards. It's hard to avoid the violent political threats that are now a regular feature of our news cycle.

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On Oct. 13, the Boston Globe spoke with Dan Bowman, a 50-year-old contractor attending a Trump rally in Cincinnati, Ohio. "If [Hillary Clinton] is in office, I hope we can start a coup," Bowman told the Globe. "She should be in prison or shot. … We're going to have a revolution and take them out of office if that's what it takes. There's going to be a lot of bloodshed."

The same day, two Trump supporters stood outside the campaign office of Democratic congressional candidate Jane Dittmar in Virginia for 12 hours while openly displaying their handguns.

On Oct. 14, three Kansas men from a militia group called the Crusaders were charged with plotting to bomb a mosque and apartment complex that is home to many Somali immigrants. The three had stockpiled firearms, ammunition and explosives. One of the plotters wrote on Facebook, "I personally back Donald Trump … Hillary Clinton cannot allowed to be in office."

On Oct. 17, at a Trump rally in Wisconsin, supporter Jared Halbrook, 25, told The New York Times that a Clinton victory could lead to "another Revolutionary War." "People are going to march on the capitols," warned Halbrook.

On Oct. 19, 40-year-old Mark Feigin of Agoura Hills, California, was arrested after threatening to kill people at the Islamic Center of Southern California. A search of his home turned up several firearms and thousands of rounds of ammunition. Hours before his arrest, Feigin tweeted, "hillary wins = end of america – start hoarding guns and ammo for the coming war."

Any doubts that these individuals could cause mass carnage should be dispelled by the gruesome shooting at The Pulse nightclub in Orlando, Florida, in June. There, one gunman armed with a semiautomatic assault rifle equipped with high-capacity ammunition magazines was able to kill 49 innocent people and injure an additional 53. In the wake of the expiration of the Federal Assault Weapons Ban (1994-2004), we are a nation awash in such weapons of war.

This reality has had little impact on mainstream Republicans, who continue to minimize calls for political violence. For example, House Speaker Paul Ryan described Trump's "Second Amendment people" threat as "just a joke gone bad." Similarly, there has been little if any pushback by the GOP against Joe Walsh's tweet.

If Ryan and other Republicans were being honest, they'd acknowledge that the concept of "Second Amendment remedies" is dangerous; and it didn't begin with Donald Trump. The so-called insurrectionist idea has been germinating for a long time in conservative politics. For 40 years, the National Rifle Association has been telling its supporters that the Second Amendment confers an individual right to shoot and kill elected leaders, law enforcement officers and military service members if they believe government is behaving in a "tyrannical" manner.

Paul Ryan, Senate Minority Leader Mitch McConnell, Republican National Committee Chair Reince Priebus, Ohio Gov. John Kasich, Sen. Marco Rubio and other GOP leaders now have a chance to safeguard our democracy – and save innocent lives – by denouncing insurrectionism once and for all.

They must tell their supporters, unequivocally, that there is no right to violent insurrection under our Constitution. They should highlight Article 1 Section 8, which states that the purpose of the militia is to "suppress Insurrections," not to foment them. And they must make it clear that trying to overthrow the American government is the work of traitors, not patriots.