(Reuters) -Billionaire businessman Elon Musk backed off digs he took at President Donald Trump after extensive outreach from administration officials, including Vice President JD Vance, with Musk saying on Wednesday he had gone "too far."

The Tesla and SpaceX CEO voiced regret after having launched an exchange of increasingly personal attacks last week on their respective social media sites by calling Trump's sweeping tax and spending bill a "disgusting abomination." In other remarks, he called it too expensive.

The feud escalated to a point where Musk threatened to start a rival political party and suggested Trump be impeached.

For investors, the open rift potentially posed multiple hurdles for Tesla, SpaceX and the rest of Musk's sprawling business empire, including Starlink, which depends heavily on its relationship with the U.S. and other governments. 

"I regret some of my posts about President Donald Trump last week. They went too far," Musk wrote in a post on his social media platform X on Wednesday, without saying which specific posts he was talking about.

He has deleted some of the posts, including the one signaling support for impeachment. He has not walked back his criticism of Trump's tax bill, however.

Vance, White House Chief of Staff Susie Wiles and David Sacks, Trump's crypto czar and a longtime Musk friend, all pushed for Musk and Trump to make up, said two people briefed on the conversations.

Asked if he had helped defuse tensions between the two, Vance told reporters at the Kennedy Center that he had spoken with Musk and Trump about "trying to ensure that Elon is publicly supporting and privately supporting the president's agenda."

He said Trump was "rightfully very frustrated" with about Musk's comments, but had no desire to be in a long-term feud with the billionaire and big campaign donor.

One of the sources said Musk was serious about potentially starting a new party, a risk for Trump's Republicans going into the November 2026 midterm congressional elections.

In the 2024 vote, Musk gave Republicans roughly $300 million, contributing to their sweep of the White House and both houses of Congress.

On Friday, James Fishback, a Tesla investor and adviser to Musk's government cost-cutting effort, posted on X that the billionaire owed Trump "a full-throated apology."

Musk retorted: "What's the apology for exactly?"

Musk subsequently deleted several posts, and a senior Trump adviser called Fishback to thank him, according to one of the sources.

Musk spoke to Trump on Monday, according to a White House source with knowledge of the matter.

Press Secretary Karoline Leavitt told reporters on Wednesday that Trump appreciated the apology. Asked if the administration was reviewing Musk's government contracts after Trump's threat last week to cancel them, Leavitt said she was not aware of any such efforts.

TESLA CONCERNS

Tesla shares were marginally lower on Wednesday. The stock has recouped most of its losses from the Trump-Musk feud, but shares are still down 19% on the year, equal to roughly $300 billion in market value.

Sales of Tesla have fallen across key markets in Europe, China and U.S. states including California as car buyers shun the company following Musk's embrace of hard-right politics in the U.S. and worldwide. 

Musk is betting big on driverless technology to grow the company, but self-driving tech is in early stages and faces skepticism. An acrimonious relationship with Trump would risk more scrutiny of Musk's business practices, as the U.S. Transportation Department regulates vehicle design standards and would have a big say in whether Tesla can mass-produce robotaxis without pedals and steering wheels.

"The conciliatory tone from Musk recently might indicate his desire to protect his businesses in the light of the position he has found himself in," said Mamta Valechha, consumer discretionary analyst at Tesla investor Quilter Cheviot.

Shawn Campbell, adviser and investor at Camelthorn Investments, said the relationship between Musk and Trump could be restored but also said it was unlikely it would return to where it once was. 

"The stakes between the richest man in the world and leader of the most powerful nation in the world are just so big, with billions of dollars of government contracts at stake, not to mention the power to investigate and regulate and tax," said Campbell, who personally holds Tesla shares.

Musk took credit for Republicans retaining a majority of seats in the House of Representatives and retaking a majority in the Senate with his cash infusion last year. Trump then named him to head an effort to downsize the federal workforce and slash spending. He left the role late last month.

Declaring their relationship over on Saturday, Trump said there would be serious consequences if Musk decided to fund Democrats running against Republicans who vote for the tax and spending bill. Trump also said he had no intention of repairing ties with Musk.

(Reporting by Alexandra Ulmer and Nandita Bose; Additional reporting by Jeff Mason, Rachael Levy, Arpan Daniel Varghese, Akash Sriram, Sruthi Shankar and Gursimran Kaur; Writing by David Gaffen, Gursimran Kaur and Timothy Heritage; Editing by Colleen Jenkins, Howard Goller, Philippa Fletcher, Nick Zieminski and Lincoln Feast.)