* As for Trump's post saying Musk "wearing thin" and going "crazy," Musk described the post as "Such an obvious lie. So sad."

* Following Trump's criticism of Musk, Tesla's stock price fell more than 15 percent on Thursday afternoon. As of this year, Tesla's share price has fallen over 30 percent.

* On Wednesday afternoon, Musk launched another broadside against the legislation, demanding his over 200 million followers on X call Senators and House lawmakers to "KILL the BILL."

WASHINGTON, June 6 (Xinhua) -- The rift between U.S. billionaire Elon Musk and U.S. President Donald Trump has been deteriorating as their extraordinary cyber war of words erupted on Thursday.

The implosion between the once-close allies was rooted in Musk's criticism of Trump's tax-cut and spending legislation that began last week. Their disagreements started over the president's bill, then quickly spiraled out of control.

A prolonged feud between Trump and Musk could deal a blow to the Republicans' fragile drive to pass their megabill, which is key to shaping both Trump's second term and the party's prospects in the 2026 midterm elections, while putting U.S. space programs at risk.

EPIC IMPLOSION

For weeks, Musk has been fiercely criticizing Trump's tax-cut and spending bill, also known as the "Big and Beautiful Bill." But the two had been careful not to hit each other directly.

On Thursday, Musk called the bill a "mountain of disgusting pork" on the social platform X. And Trump broke his silence, telling reporters in the Oval Office he was "very disappointed" in Musk.

"Look, Elon and I had a great relationship. I don't know if we will anymore," Trump said. "I'm very disappointed in Elon. I've helped Elon a lot."

In response, Musk accused Trump of being ungrateful for the millions he spent to get him elected.

"Without me, Trump would have lost the election, Dems would control the House and the Republicans would be 51-49 in the Senate," Musk wrote on X on Thursday afternoon.

As for Trump's post saying Musk "wearing thin" and going "crazy," Musk described the post as "Such an obvious lie. So sad."

Trump threatened to take away all contracts from Musk's companies, including the SpaceX firm that has been a critical player for NASA.

"The easiest way to save money in our Budget, Billions and Billions of Dollars, is to terminate Elon's Governmental Subsidies and Contracts," Trump posted on Truth Social.

Following Trump's criticism of Musk, Tesla's stock price fell more than 15 percent on Thursday afternoon. As of this year, Tesla's share price has fallen over 30 percent.

Musk was once a staunch ally of Trump, spending nearly 300 million U.S. dollars to support Trump's campaign in 2024. After Trump won the presidential election, Musk joined the newly established Department of Government Efficiency (DOGE), responsible for overseeing bureaucratic corruption and reducing the national debt.

DOGE's work led to thousands of federal government layoffs and cuts of billions of dollars in foreign aid and other programs, sparking multiple protests in the United States and around the world. On Wednesday last week, Musk announced his departure.

"KILL THE BILL"

Trump's megabill is a legislative package combining tax and spending cuts with provisions on such issues as border security, energy exploration and welfare reform.

The bill includes 1.2 trillion dollars in spending cuts over a decade but would raise deficits by 2.4 trillion dollars compared with doing nothing, according to a Congressional Budget Office estimate released Wednesday. "This massive, outrageous, pork-filled Congressional spending bill is a disgusting abomination. Shame on those who voted for it: you know you did wrong. You know it," said Musk in his posts on X after quitting his leading position at DOGE a few days ago.

The billionaire entrepreneur has been a vocal critic of the legislation, especially its proposed elimination of electric vehicle (EV) tax incentives. Given Tesla's position as a leading global EV manufacturer, Musk's opposition appears both predictable and justified.

On Wednesday afternoon, Musk launched another broadside against the legislation, demanding his over 200 million followers on X call Senators and House lawmakers to "KILL the BILL."

Trump said Musk's dissatisfaction stemmed from the bill's proposal to eliminate tax credits for EV consumers, which affected Musk's interests as CEO of Tesla.

Musk, however, said he opposed the bill because it would increase the federal deficit. He pulled up past quotes from Trump decrying the level of federal spending, mocking, "Where is this guy today?"

WHAT'S THE FUTURE

Trump's megabill passed last month in the House by a 215-214 vote, and is currently waiting for Senators' deliberation. The bill, key to the U.S. president's domestic agenda, could shape both his second term and the Republican prospects in the 2026 midterm elections.

But Musk's opposition has thrown a wrench into the Republicans' fragile push for their megabill, which includes tax cuts and border spending, partially offset by trims to Medicaid, clean-energy tax credits and food aid.

Musk's social media posts rallied fiscal conservatives in the Republican Party, but it wasn't clear if it would make a difference given Trump's strong backing of the current package.

The ongoing tussle between Trump and Musk might hinder Republicans' chances of maintaining control in Congress during next year's midterm elections.

Besides his campaign contributions, Musk boasts a substantial online presence and has played a role in linking Trump to segments of Silicon Valley and affluent donors.

Soon after Trump's Oval Office comments, Musk polled his followers on X: "Is it time to create a new political party in America that actually represents the 80% in the middle?" As of Thursday night, the poll had drawn more than 4 million votes, with over 80 percent voting "Yes."

In response to Trump's threat to terminate government contracts with Musk's companies, Musk said he would begin "decommissioning" SpaceX's Dragon spacecraft, which is the only U.S. spacecraft capable of sending astronauts to the International Space Station.

Hours later, Musk appeared to walk back the threat, replying to a follower urging both sides to "cool off." "Good advice. Ok, we won't decommission Dragon," he wrote.

Even so, the clash raised concerns that if the president does cancel billions of dollars of SpaceX contracts with NASA and the Pentagon, Musk could pull his Dragon spacecraft out of service. Without it, multiple U.S. space programs would fall apart.

Without commenting on SpaceX, Bethany Stevens, NASA's press secretary, wrote on X late Thursday afternoon, "We will continue to work with our industry partners to ensure the President's objectives in space are met."(Video reporters: Hu Yousong; video editors: Hong Ling, Hui Peipei, Zhang Mocheng)