Megabill negotiations show Vance is a key player in the Trump administration

Over the past six months, Vice President JD Vance has shown how much of a key player he has become in the Trump administration, serving as the president's most prominent advocate and advancing his agenda.

The latest example came this week, when Vance helped push President Donald Trump's massive tax and spending bill through Congress.

Vance held a series of meetings with conservative and moderate holdouts and Senate leadership last Saturday to help move the bill forward. A source with direct knowledge stated that Vance played a key role in talking with Senate holdouts throughout the bill before he ended up casting several tie-breaking votes as president of the Senate and move the spending bill along to the House.

Republican Sen. Lisa Murkowski, who had been critical of the bill's cuts to Medicaid and SNAP -- the food assistance program -- met with Vance, where he thanked her for being a team player despite her concerns with the legislation, just before she voted for the bill.

During the sprint to push the bill through, Vance was criticized for his social post around concerns of the bill's impact on Medicaid, writing that "the minutiae of the Medicaid policy—is immaterial compared to the ICE money and immigration enforcement provisions."

During all this, Vance was making phone calls to Trump and the two were updating each other on their talks with senators ahead of the bill's passage.

The vice president attended Wednesday's meeting at the White House between Trump and several holdouts from the House as the president ramped up the pressure to vote for the bill.

North Carolina GOP Rep. Greg Murphy, who had told reporters on Wednesday night that he was still undecided because of some of the health care provisions, said Thursday that he ultimately decided to support the package after speaking on the phone to Vance and the president.

"I needed assurances," he said.

A source close to Vance said that he continued to work the phones ahead of the floor vote on the rule, calling multiple House GOP holdouts to make the administration's case for them to support the bill.

However, it's not just on the domestic policy front that Vance is having an impact. He has also been critical in supporting Trump's foreign policy.

While Trump was weighing the decision to strike Iran's nuclear sites, Vance came to the president's defense after supporters like Tucker Carlson and those in the MAGA base were outspoken against the U.S. getting involved in the conflict between Israel and Iran.

"He may decide he needs to take further action to end Iranian enrichment. That decision ultimately belongs to the president," Vance wrote on X. "And of course, people are right to be worried about foreign entanglement after the last 25 years of idiotic foreign policy. But I believe the president has earned some trust on this issue. And having seen this up close and personal, I can assure you that he is only interested in using the American military to accomplish American people's goals. Whatever he does, that is his focus."

Vance's comments were a departure from his prior statements that the U.S. should not get entangled in foreign conflicts.

A prime example is the vice president's opposition to the U.S. providing more aid to Ukraine.

"I gotta be honest with you, I don't really care what happens to Ukraine one way or another," Vance said in February 2022, amid an explosion of bipartisan support for the country following the aftermath of Russia's invasion.

Most recently, Vance expressed concerns about the president's decision to strike the Houthis in Yemen in a Signal group chat with other top administration officials.

"I am not sure the president is aware how inconsistent this is with his message on Europe right now," Vance wrote in the chat. "There's a further risk that we see a moderate to severe spike in oil prices. I am willing to support the consensus of the team and keep these concerns to myself. But there is a strong argument for delaying this a month, doing the messaging work on why this matters, seeing where the economy is, etc."

In the lead-up to the strikes, Trump was trying to engage the MAGA base with Vance to see what their reaction would be if he ordered the bombing.

Prior to the strikes, Trump told reporters on Air Force One while flying back from the G7 summit in Canada that it was possible he could send Vance and special envoy Steve Witkoff to meet with Iranian negotiators.

Vance's active role in moving Trump's agenda forward was always part of the plan.

In November, following the election, a source close to the vice president told ABC News that Vance had been tasked to ensure that all of the priorities of the Trump administration move forward and would work on any of the issues Trump needed him to further, signaling that the vice president would not be assigned one specific issue to work on, but would be involved in several policy issues.

It was also expected that Vance would be Trump's "eyes and ears" in the Senate to ensure that his agenda moves forward, the source also said. It's familiar territory for Vance, who was elected to the Senate in 2022.

All this comes as Vance is viewed by some as the MAGA heir apparent to Trump ahead of the 2028 election. At the same time, he is working to raise as much money as possible for Republicans ahead of the 2026 midterms as chair of the Republican National Committee -- the first time a vice president has ever held the role.

Joel Goldstein, a vice-presidential scholar and former professor at Saint Louis University Law School, told ABC News that Vance is working in a different timeline compared to his predecessors, as he will serve only one term as vice president under Trump.

"Every vice presidency is different and one of the things that is unique about Vance's is that every other vice president, you know, with the possible exception of Harris, entered office with the expectation that the president was going to run for reelection," Goldstein said.

"I think he's in a very unique position in that his first term as vice president is his last, and so his presidential ambitions, the time for reckoning comes up, you know, much quicker than is normally the case."

Following his tie-breaking votes in the Senate, several Democrats who might be opponents in the 2028 presidential election attempted to make Vance the face of Trump's spending bill.

In a post on X, former Transportation Secretary Pete Buttigieg called out Vance for casting the tie-breaking vote to allow the bill to move forward.

"VP Vance has cast the deciding vote in the Senate to cut Medicaid, take away food assistance, blow up the deficit, and add tax breaks for the wealthiest," Buttigieg wrote. "This bill is unpopular because it is wrong," he continued.

California Democratic Gov. Gavin Newsom told Americans on X to "bookmark" this moment, writing that "JD Vance is the ultimate reason why 17 million Americans will lose their healthcare."

In an interview with NBC News, Trump pointed to Vance and Secretary of State and interim national security adviser Marco Rubio as possible successors, and said, when asked, that he believes his MAGA movement can survive without him.

Asked about the president's comments, Vance said that if he does end up running for president, he's "not entitled to it."