Donald Trump wants his ridiculous (and unneeded) border wall -- and he doesn't care who he has to hurt to get it. He tried to separate immigrant children and hold them hostage to get Congress to fund his wall. That just upset Americans, and it looks like he is rescinding that horrible policy.
He has tried the same thing with the Dreamers, saying he would protect them if Congress gave him his wall. But Congress has been unable to agree on immigration reform, and that won't happen before the November elections (if at all).
Now he wants the full funding (about $25 billion) in the budget that must be approved by the end of September. Upon learning that is not at all likely to happen, he is now threatening to shut down the government by refusing to sign the new budget (if it doesn't have full funding for the wall). He doesn't seem to care who would be hurt by a shut down (including Republicans running for re-election).
Here is how Burgess Everett at Politico describes it:
In a private meeting regarding the wall Monday, Trump fumed at senators and his own staff about the $1.6 billion the Senate is planning to send him this fall, according to two people familiar with the meeting. Trump wants the full $25 billion upfront and doesn’t understand why Congress is going to supply him funds in a piecemeal fashion — even though that’s how the spending process typically works. . . .
The president said at the meeting that if Congress doesn’t give him the resources he needs for border security, he will shut down the government in September, according to one of the people familiar with the meeting. He did not give a specific number, but has been fixated on getting the $25 billion in a lump sum. . . .
Senate Democrats offered to provide $25 billion in border wall funding earlier this year in return for giving 1.8 million young undocumented immigrants a pathway to citizenship. But Trump and most Republicans rebuffed that proposal to salvage the Deferred Action for Childhood Arrivals program. Democrats are unlikely to provide $25 billion for Trump's wall absent a much broader immigration deal. . . .
On Monday, GOP Sens. Shelley Moore Capito of West Virginia and Shelby both tried to explain to Trump that the Senate is merely meeting Mulvaney’s request and has to cut a bipartisan deal with Democrats. The Senate needs 60 votes to pass a spending bill, so Republicans would have to find at least nine Democratic votes. . . .
But Trump has not been mollified. He raised his voice several times in Monday's meeting with Mulvaney, White House staffers and the senators, insisting he needs the full $25 billion — an unlikely outcome in the narrowly divided Senate.