Washington CNN  — 

President Donald Trump spent the last two days insisting that he was ready to find compromise on gun control measures in the wake of the murders of 17 people at Marjory Stoneman Douglas High School in Florida last week.

He expressed support for expanded background checks and for raising the age to buy a rifle from 18 to 21 and argued that he wasn’t at all worried about blowback from the National Rifle Association.

That all changed during Trump’s speech Friday morning at the Conservative Political Action Conference just outside Washington. Talking about the stakes of the 2018 election, Trump said that if Democrats win back control of Congress “they’ll take away your 2nd Amendment.”

As he closed his speech, Trump again said Democrats want to repeal the 2nd Amendment: “They will do that, they will do that,” he said.

Which is, of course, not true. It is also hugely toxic to any attempt to find shared ground on the sort of “common sense” changes to gun laws that Trump, um, trumpeted later in his CPAC speech.

Let’s start with the logistical fallacy at the heart of Trump’s claim.

In order to “take away your 2nd Amendment,” two-thirds of the House and Senate would need to approve of a proposed Constitutional amendment to repeal the 2nd Amendment. If that happened, the proposed amendment would go to each of the 50 state legislatures, where it would face an up-or-down vote. Three-quarters of those states – 38 – would need to approve of the amendment repealing the 2nd Amendment. If they did, the 2nd Amendment would be gone.

Two-thirds of the House and Senate would never agree on this. And even if they did, there is a 0% chance that 38 state legislatures would OK such a plan. Republicans currently have majorities in both the state House and state Senate in 32 states. Thirty-two!

Trump, of course, isn’t really engaged in the math of repealing a constitutional amendment. And he’s banking on the fact that none of the CPAC crowd cheering for that line has any real sense of the logistical unlikelihood of Democrats getting rid of of their right to bear arms.

What Trump is doing is trying to scare people into voting. If you don’t turn out to vote this November, Democrats are going to take control of Congress. Then they’ll repeal the 2nd Amendment. And that’s when they come to your house and collect your gun(s).

In doing so, Trump is aping a longtime tactic of the NRA – casting the entire gun debate as a slippery slope. Give an inch on gun control – universal background checks, for example – and open Pandora’s box to the true motive of gun control fanatics: National gun collection.

“You should be anxious and you should be frightened,” NRA CEO Wayne LaPierre told the CPAC crowd 24 hours before Trump spoke. “What they want is more restrictions on the law-abiding. They want to sweep right under the carpet the failure of school security.”

This sort of all-or-nothing thinking is a massive impediment to any change – even on something like universal background checks, which has near-unanimous support – on gun laws.

Trump’s pivot from compromiser-in-chief to flamethrower-in-chief on guns should surprise exactly no one. He did a very similar about-face on immigration – voicing support for comprehensive immigration reform on a Tuesday and then walking away from any sort of compromise deal on a Thursday.

This is a day-to-day president. What he says one day means nothing about what he will say the next. Whether it’s guns or immigration, Trump is, at his core, fundamentally changeable. He will say what gets him applause. And he will change that view on a dime.

Don’t get fooled again. Whatever Trump says on guns tomorrow – and it might be the opposite of what he said today – is indicative of absolutely nothing.