The White House has been uncharacteristically muted on the upcoming Senate vote to overturn Trump's declaration of a national emergency on the southern border. (While passage would be a severe blow to Trump's pride, there seems little chance that the Republican-held Senate would be able to override the assured Trump veto.)
Behind the scenes, though, the White House appears to be putting the screws to wavering Republican senators, warning them that if they vote against Dear Leader's declaration of invisible emergency, then Dear Leader will take that very personally indeed.
In recent days, White House officials have conveyed a stern message to GOP senators, especially those up for re-election in 2020: There will consequences if they vote with the Democrats and defy the President. They have vowed it will affect their standing with the administration and there will be retribution, including potential primary fights.
This isn't so much a warning as it is a statement of fact. Donald Trump operates primarily by grudge. If you support him, he likes you; if you get in his, way he hates you. And there's nothing between. It is all but assured that any Republican who votes against Trump's self-promotional "emergency" will find themselves permanently on Trump's enemy list, the target of angry tweeting and obsessively crafted insults, including Trump’s support for whatever no-name idiot the base might put forth as a primary opponent. This isn't about policy—this is about loyalty. Dear Leader decreed that the sky is green, not blue; insist it is green or face his wrath.
We can probably deduce from this White House outreach that Trump, hearing reports of as many as ten possible Republican defectors, blew one of his few remaining gaskets and told staff to somehow fix the situation he finds himself in. But it's also perhaps a signal that even Trump is recognizing he's in danger of losing his grip on the Senate. It's vanishingly unlikely the Senate will override his veto, but even passing a bill requiring his veto signals a hint of Senate independence—enough to make an unindicted criminal co-conspirator sweat a bit.