(WASHINGTON) -- Senate Republican Leader John Thune reiterated that "failure is not an option" as he works to get GOP holdouts on the megabill advancing President Donald Trump's legislative agenda in line -- especially amid Elon Musk's efforts to tank the bill.
"This is a team effort, and everybody is going to be rowing in the same direction to get this across the finish line. Failure is not an option, and we intend to deliver, along with the president for the American people on the things that he committed to do and that we committed to do in terms of the agenda," Thune told reporters after he left a meeting with Trump at the White House on Thursday.
As things currently stand, Thune can afford to lose only three of his GOP members to pass the package, and right now, he has more members than that expressing serious doubts about the bill.
The House-passed legislation extends the Trump 2017 tax cuts, boosts spending for the military and border security -- while making some cuts to Medicaid, SNAP and other assistance programs. It could also add $3 trillion to the deficit over the next decade, according to an analysis out Wednesday from the nonpartisan Congressional Budget Office.
As the Senate weighs possible changes to the state and local tax (SALT) deduction cap as part of the tax portion of the bill, House Republicans from blue states are already threatening to derail the bill's prospects.
"Let's be clear — no SALT, no deal," New York Republican Mike Lawler said Wednesday in a post on X.
New York Rep. Nick LaLota is on the same page, posting on X: "No SALT. No Deal. For Real."
The House-passed bill raises the deduction limit of state and local taxes from federal income tax filing from $10,000 to $40,000 for joint filers making less than $500,000 per year. The cap increases then by 1% every year thereafter.
Thune signaled changes could be coming to the SALT deal that was struck in the House, but the details are still unclear.
"It would be very, very hard to get the Senate to vote for what the House did," Thune told reporters. "We've just got some people that feel really strongly on this."
Speaker Mike Johnson said he spoke to the SALT caucus on the floor during House votes Wednesday and plans to "communicate" their red line with Senate leaders.
The SALT deal is "a very delicate thing and we have to maintain the equilibrium point that we reached in the House, and it took us almost a year… so I don't think we can toss that," Johnson said.
Musk's effect on negotiations
Not helping Thune's endeavor to sway the defectors are frequent posts from Musk targeting the bill -- and on Thursday targeting the president.
Musk on Thursday quoted a 2013 post from Trump criticizing Republicans for extending the debt ceiling, with Musk writing, "Wise words." The two feuded on Thursday, with Trump threatening to "terminate Elon's governmental subsidies and contracts."
Earlier, Musk slammed the bill, calling it a "disgusting abomination" and later urged all members of Congress to "kill the bill."
Trump touted the bill from the White House on Thursday -- brushing off the scathing criticism from Musk.
"I'm very disappointed because Elon knew the inner-workings of this bill better than almost anybody sitting here better than you people. He knew everything about it. He had no problem with it. All of a sudden he had a problem," Trump said.
Johnson said he planned to speak directly to Musk on Thursday, a day after the speaker said the billionaire was "flat wrong" in his criticism of the bill. Multiple administration officials have attempted to reach out to Musk and his representatives personally, but their calls and texts have not been returned, several sources tell ABC News.
Before speaking out publicly against the bill, Musk personally pushed some lawmakers, including Johnson, to keep the tax credits for electric vehicles in the bill, according to two people familiar with conversations.
Musk criticized Johnson in a post on X on Thursday, pointing to a 2023 post where Johnson attacked the federal debt.
"Where is the Mike Johnson of 2023!?" Musk asked.
Johnson defended himself and emphasized the importance of passing the "big, beautiful bill," posting that the "Mike Johnson of 2023 is the SAME Mike Johnson who has always been a lifelong fiscal hawk - who now serves as Speaker and is implementing a multi-stage plan to get our country back to fiscal responsibility and extraordinary economic growth."
Thune said Wednesday that although he can't speak to Musk's motivations for his opposition, he will continue to push for the bill's success in the Senate.
Musk's public bashing of the bill came up in senators' meeting with Trump on Thursday, said Republican Sen. Roger Marshall, describing it as a "laughing conversation for 30 seconds."
"It was very much in jest and laughing, and I think he said something positive about Elon appreciating what he did for the country," Marshall said.
ABC News' Will Steakin, Rachel Scott Mary Bruce, Molly Nagle and Kelsey Walsh contributed to this report.