MSNBC just aired video of a man with a pistol strapped to his leg waiting for Barack Obama to arrive at a townhall in New Hampshire.

The man is carrying a sign that says, "It Is Time to Water the Tree of Liberty." That's a reference to a Thomas Jefferson quote: "The tree of liberty must be refreshed from time to time, with the blood of patriots and tyrants." It was a favorite slogan of Oklahoma City bomber Timothy McVeigh, who was wearing a T-shirt when he was arrested with a picture of Lincoln on the front and a tree dripping with blood on the back.

Now, this guy is carrying a legal weapon, says NBC News' Ron Allen. The local chief of police has no objections. Open carriage of licensed handguns is legal in New Hampshire, and the man is standing on the private property of a nearby church (!) that has no problem with an armed man hanging around.

But let's be clear: anyone watching the mounting rage over, of all things, health care — perhaps one of the most boring and complex policy subjects — has to worry that these people are going to try to kill Barack Obama. That's not an extrapolation from unhinged rhetoric, or a partisan reading of the imagined intentions of our political enemies. It's a rational reading of the anticipated behavior of a man who brandishes a gun at the location where the president is expected to imminently arrive while holding a sign that openly advocates his assassination. And the astonishing, breathtaking, maddening fact that he hasn't been violently taken to the ground by large men wearing suits and earpieces is an open encouragement to anyone else so inclined to give it a shot.

There are always people who want to kill the president. Generally speaking, they are politically marginalized, insane, and/or too incompetent to come close to achieving their ends. But in the past six months, people who would be inclined to do violence to our political leaders have been affirmatively embraced by the Republican Party and its messaging operation. It's as if there had been a 24-hour cable news channel in 1981 devoted to coverage of Jodie Foster, and what it would take for someone to get her attention. Here's what you get when you have a partisan political establishment that openly trades in themes of violence, xenophobia, paranoia, illegitimacy, and revolution:

And here is a town hall this morning where Sen. Arlen Specter (R... I mean D-Pa.) faced a man threatening judgment from God:

Did extremists on the left adopt the same tone against Bush? Yes. And there is an element in this wingnuttery of the same sort of dispossessed rage and periodic venting that many liberals felt under the last administration. But it's different when that rage is being purposefully manipulated to (imagined) political advantage by the GOP. And it's different when there's actually a guy with a gun waiting for the president to show up.

Middle video compiled by Mike Ragan; bottom video by Mike Byhoff.