President Trump sent two big signals Tuesday about separating families who immigrated illegally at the border:

One, he is not backing down and says he can't reverse the policy without congressional action.

And two, he has no idea what specific action he's demanding.

From Day One, Trump's zero-tolerance gambit has clearly been about forcing Congress's hand by creating a hugely undesirable situation at the border. The White House insists this isn't a new policy and that it's not about creating a bargaining chip. But it is a new policy, based upon a new supposed interpretation of the law, and Tuesday's speech made clear that Trump is holding a knife to Congress's throat.

And while the policy would still be cruel, his tactic make sense if Trump knew what he wanted. But even as the House was prepared to take up two immigration bills this week — bills the White House has said Trump would sign — Trump decided to throw a wrench in the whole thing. Contrary to what his own White House said, Trump said Tuesday that he would be seeking changes to the House immigration bills after he reviewed them.

“We have a House that’s getting ready to finalize an immigration package that they’re going to brief me on later,” Trump said, “and that I’m going to make changes to.”

That sound you just heard is House Speaker Paul D. Ryan (R-Wis.) and his House colleagues losing their lunch.

Ryan has given assurances that he has been working closely with the administration through the process of crafting both a bill supported by GOP leadership and a more conservative alternative spearheaded by Rep. Bob Goodlatte (R-Va.). And on Saturday, White House spokesman Raj Shah said clearly that Trump was on board with both: “The President fully supports both the Goodlatte bill and the House leadership bill. . . . He would sign either the Goodlatte or the leadership bills.”

That all appears to be in doubt now, thanks to a few utterances from Trump.

This is hardly surprising. The assurance from Shah on Saturday came after Trump appeared to say he wouldn't sign the leadership's more moderate bill. The White House tried to play it off as a misunderstanding, but Tuesday's comments make it pretty clear that Trump has had reservations — or at least, that he isn't truly committed to anything.

And we've been down this road before — in the last immigration debate, in fact. Trump repeatedly moved the goal posts on what he wanted from an immigration package and even appeared to pull the rug out from beneath a bipartisan Senate package that had the key elements he had asked for. After that episode, Sen. Lindsey O. Graham (R-S.C.), a key negotiator, made it clear that Trump changed his stance in a couple of hours one morning, and said he was dumbfounded by Trump's late 180. “So what happened between 10 [a.m.] and 12?” Graham said. “I don't [know], either, and I'm going to find out.”

Trump has offered similarly mixed messages about what he wanted on issues from health care to gun control to tax cuts, often appearing not to understand the legislative process or policy basics.

But it's one thing to do that on regular policy; it's another to do it once you've decided to take the drastic step of separating young children from their parents — a situation Trump admits is awful, while maintaining that he has no other choice. The longer this situation drags on, the more potential damage is done to young people. And that means having a clearly defined endgame is vital.

But Trump has never demonstrated consistency in what he wants or even curiosity about the details of what's working its way through Congress, and that again appears to be the case. That makes ending this whole awful episode much more difficult, and Trump's whole posture here even more maddening, for his party — and quite unnecessarily so.