Musk backs Sen. Paul's criticism of Trump's megabill in first comment since it passed

Tesla CEO Elon Musk, who bombarded President Donald Trump's signature spending bill for weeks, on Friday made his first comments since the legislation passed.

Musk backed a post on X by Sen. Rand Paul, R-Ky., who said the bill's budget "explodes the deficit" and continues a pattern of "short-term politicking over long-term sustainability."

CNBC has reached out to the White House for comment.

The House of Representatives narrowly passed the One Big Beautiful Bill Act on Thursday, sending it to Trump to sign into law.

Paul and Musk have been vocal opponents of Trump's tax and spending bill, and repeatedly called out the potential for the spending package to increase the national debt.

On Monday, Musk called it the "DEBT SLAVERY bill."

The independent Congressional Budget Office has said the bill could add $3.4 trillion to the $36.2 trillion of U.S. debt over the next decade. The White House has labeled the agency as "partisan" and continuously refuted the CBO's estimates.

The bill includes trillions of dollars in tax cuts, increased spending for immigration enforcement and large cuts to funding for Medicaid and other programs.

It also cuts tax credits and support for solar and wind energy and electric vehicles, a particularly sore spot for Musk, who has several companies that benefit from the programs.

"I took away his EV Mandate that forced everyone to buy Electric Cars that nobody else wanted (that he knew for months I was going to do!), and he just went CRAZY!" Trump wrote in a social media post in early June as the pair traded insults and threats.

Shares of Tesla plummeted as the feud intensified, with the company losing $152 billion in market cap on June 5 and putting the company below $1 trillion in value. The stock has largely rebounded since, but is still below where it was trading before the ruckus with Trump.

-- CNBC's Kevin Breuninger and Erin Doherty contributed to this article.