As the House of Representatives was about to take a break for the afternoon on Wednesday, Democrats did something that has only been done twice before since the 1970s: seize the floor to demand a vote, specifically on gun control measures.

"Sometimes you have to do something out of the ordinary," said Rep. John Lewis (D-Ga.), a civil-rights icon, who led his own sit-ins at segregated lunch counters in Tennessee decades ago. "Sometimes you have to make a way out of no way."

A few hours after it started, it's still going strong:

It even got support from the highest levels of U.S. politics:

While dramatic and rare, we're skeptical this sit-in will actually lead to changes in Congress's unwillingness to consider gun control legislation. It almost certainly won't change any actual votes. And as we've seen for decades now — and especially this past week — the votes just aren't there to change the country's gun laws.

Here's the specifics for why this sit-in is likely to lead to not very much.

House Democrats want a vote to address gun violence, but it's not immediately clear exactly what sort of vote that might be. And that vagueness could be a problem, because as the Senate has illustrated this week, there is a very, very narrow window of compromise here.

After an equally dramatic 15-hour filibuster by Senate Democrats in the days after the Orlando massacre, the Senate voted on four different proposals that in the past had drawn bipartisan support. All four failed.

Right now, anyone on the FBI's various terrorist watch lists can legally buy a gun. Senate Republicans and Democrats both agree that suspected terrorists shouldn't be able to do that, but they're split on whether to let the attorney general ban people from buying guns before or after the courts have a chance to weigh in.

To state the obvious, what fails in the Senate is almost certainly doomed in the House. The composition of the House is much more conservative than the Senate: Republicans have their largest majority since World War II in the lower chamber, while Senate Republicans have only a slight majority.

And sit-ins have happened before to little effect. According to Matt Green, a political scientist at Catholic University who's written a book about House minority party tactics, Democrats have even been on the receiving end of the sit-in.

In 1995, House Democrats spent a few hours on the floor in protest of a budget that House Republicans passed. In 2008, House Republicans seized the floor in August for the entire recess to demand Democrats let them vote on oil drilling to lower $4-a-gallon gas prices. They ended up getting a vote, but more because Democrats feared the sit-in would endanger Barack Obama's presidential campaign.

This time around, House Democrats' hopes of turning their sit-in into any kind of legislative victory would seem to rest on the sliver of compromise introduced Tuesday by Sen. Susan Collins (R-Maine). Collins wants to let the attorney general stop people on two of the FBI's most serious terrorist watch lists from being able to buy guns. That amounts to about 2,700 Americans.

Like we said, it's a narrow window of compromise. And like any good compromise, there are some Republicans who support it, and some Democrats who support it. But no one's really enthusiastic about it.

A lack of enthusiasm is exactly what House Democrats are up against, and exactly why they're staging this sit-in.

If a majority of Congress isn't particularly gung-ho about the one piece of legislation that could actually pass the Senate, House Republicans have absolutely no incentive to bring it up for a vote. Why would Speaker Paul Ryan risk taking a politically divisive vote on guns when he's not getting pressure from his party to take it? He's got enough problems to deal with.

Indeed, Ryan indicated as much when he told reporters Wednesday he probably wouldn't bring this compromise up for a vote unless it did really, really well in the Senate. And as The Post's Karoun Demirjian reports, we don't know if the Collins compromise can even pass the Senate, let alone fly through it.

So we're back to where we started. No big breakthrough in the gun debate after Orlando. No enthusiasm for the one compromise on gun control in Congress. And no real viable political path to passing any gun control measures in this Congress — sit-in or not.