As absolutely delicious as the personal drama between Elon Musk and Donald Trump is--and as much as it may escalate into everything from robotaxis to SpaceX and national defense--let's not lose sight of the deficit fight that's at the heart of it. 

Musk's beef with Trump after he was dismissed from service first erupted over the "One Big Beautiful Bill." A "disgusting abomination," Musk called it on X this week. "Shame on those who voted for it."

He went on to repost tons of old tweets from Trump, along with current Senate and Congressional Republican leaders, calling out their hypocrisy for criticizing past debt levels and deficits even as they now support a bill that would raise the debt ceiling by trillions and increase deficits by $2.4 trillion over the next decade. 

Yesterday, when asked about Musk's criticism--which could sink the entire bill, if enough Senate Republicans like Ron Johnson and their constituents turn against it--the president chalked it up to sour grapes over the bill's failure to extend EV tax credits. But Musk insists that's not the case, and few really expected the credits to be continued anyway. 

No, it seems Musk's real beef, assuming this isn't just a convenient way for him to reposition himself with the broader public, seems to be over the cost of Trump's megabill. 

But here's the rub. This isn't just any old stimulus act, or grab-bag of political preferences. There is a ticking time bomb hanging over the economy this year,  because Trump's first-term tax cuts are going to expire at year-end. The cost of this bill isn't over new stuff they want to do--it's mostly just extending the status quo. That alone costs $4 trillion over the next decade. 

So while it's a very attractive argument that Musk is making--how dare they now raise the debt ceiling and make the whole fiscal situation even worse!!--I'd love to know what exactly he would propose doing instead. Would he prefer that taxes go up on households and businesses next year? Fine, if so; that's the Democratic party's position. But I have yet to hear him embrace that either tactically or philosophically. 

This is where the issue of "SALT" comes in. It would cost $377 billion over the next decade, according to Heritage, to quadruple the cap--and this would be new tax relief. But again, this is a small percentage of the overall cost. And it could be the difference between Republicans keeping their tiny majority in the House, or not. 

House Speaker Mike Johnson made this clear on Squawk Box this morning. "If we don't deliver on this [bill], and we don't deliver a little bit on SALT relief, then we're not going to have the House majority," he said. "And if the Democrats take over, they will impeach Donald Trump...and everything will go to chaos. So this team has to stay in power." He also implied Democrats would deliver even worse fiscal outcomes. 

But perhaps none of that matters to Musk, who would practically seem to be leading the impeachment drive, the way things are going this week. Perhaps he disagrees that Democrats would be worse for the fiscal situation. Or perhaps he senses that that party would now be much more sympathetic to his EV and robotaxi ambitions. 

Point being, if Musk blows up the budget bill, and takes a hard fiscal line on any subsequent negotiations, the GOP isn't going to turn around and gut Medicare or Medicaid--which it's struggling to pare back at all right now--in order to balance the budget. No, it just means that taxes are going up at year-end. 

See you at 1 p.m!

Kelly

Twitter: @KellyCNBC

Instagram: @realkellyevans