Centrist Sen. Joe Manchin (D-W.Va.) is the most pivotal vote in the evenly divided Senate, and his power could spark prolonged intraparty feuds among Democrats.

Concerned about simmering friction, Senate Majority Leader Charles Schumer (D-N.Y.) on Tuesday strongly urged his Democratic caucus to unify around a pending $1.9 trillion COVID-19 relief package. 

Manchin appears to have derailed President Biden’s nominee to head the White House budget office, Neera Tanden, by announcing last week that he would vote against her because of sharp criticisms she leveled on Twitter against Senate colleagues. In a 50-50 Senate, Tanden now needs the backing of at least one Republican, and perhaps more, which appears unlikely.

Manchin has jeopardized Biden’s plan to raise the federal minimum wage to $15 an hour by announcing this month he opposes such an increase. He suggested instead setting it at $11 an hour and indexing it to inflation.

Asked about Manchin’s impact on the Democratic agenda, Schumer told reporters Tuesday that he called on his colleagues to work together. 

“I made a pitch today to our entire caucus and I said that we need to pass this bill. The American people, the American public demands it,” Schumer said after holding a call with Democratic senators.

Schumer said that not every Democratic senator is going to be entirely pleased with the COVID-19 relief bill but warned the party must pass it. In all likelihood, every Democrat in the upper chamber will have to back the measure in order to get it to the president’s desk.

“Job No. 1 is to pass the bill. Pass the bill we must. And I have confidence we will do it,” Schumer added.

Manchin on Monday said he would attempt to amend Biden’s $1.9 trillion relief proposal, which the House is scheduled to pass this week, to set the federal minimum wage at $11 an hour.

“Eleven dollars is the right place to be,” he said. “I’d amend it to $11.” He also added that his plan is to index the wage floor to inflation.

The Senate parliamentarian is also expected to rule soon on whether Democrats can include minimum wage in their budget reconciliation bill. Biden has indicated he doubts she will allow it, but progressives disagree. 

Passing Biden’s pending $1.9 trillion relief package, however, is only the start of the challenges facing Schumer, Manchin and the rest of the Democratic caucus.

“I talked to Harry Reid about him and he said [Manchin] was always a pain in the neck,” said Ross K. Baker, a professor of political science at Rutgers University who served as a fellow in the office of former Senate Majority Leader Harry Reid (D-Nev.).

“[Manchin is] in an awkward position. He’s a Democrat from a state that backed Trump more heavily than any other state,” Baker added, noting that former President Trump carried West Virginia with 68 percent in 2016 and 69 percent in 2020. In 2020, Trump gained a larger percentage of the vote only in Wyoming — 70 percent.

The 73-year-old senator is not up for reelection until 2024. He won his last election contest by 3 points, a race he later said “took a toll” on him. 

Manchin’s support is far from certain if Democrats try to pass Biden’s “Build Back Better” jobs and economic recovery plan.

Senate Budget Committee Chairman Bernie Sanders (I-Vt.), who is pushing hard for a $15 an hour wage bill, said discussions are already underway about using special budgetary rules to pass a massive economic stimulus package with a simple majority vote after the $1.9 trillion “American Rescue Plan” becomes law.

Manchin said Tuesday that Democratic leaders should move an infrastructure and jobs bill, which may cost as much as $3 trillion, through regular order, which means working with Republicans instead of using another budget reconciliation package to bypass GOP colleagues.

“I want to make sure we go back to some regular order. It should go through the committee[s]. These are big things that need to be done, they are policy changes, and I would like to use the committee process and if anyone understands that better than Joe Biden, I don’t know who that would be,” he said. “We’ve got to get back to regular order.”

Asked if he had reservations about using special budget rules to pass a second package, he said: “Regular order. Let’s try. Let’s try and see if the place will work first.”

Manchin, who chairs the Senate Energy and Natural Resources Committee, also raised doubt this week about another one of Biden’s nominees, Rep. Deb Haaland (D-N.M.). His spokeswoman said the senator is undecided on Haaland, who would be the first Native American to head the Interior Department or serve in the Cabinet.

That prompted a stern rebuke from liberal Rep. Alexandria Ocasio-Cortez (D-N.Y.), who juxtaposed Manchin’s indecision over Haaland to his support for Trump’s nomination of Jeff Sessions in 2017 to head the Department of Justice.

“Manchin voted to confirm him. Sessions then targeted immigrant children for wide-scale human rights abuses w/ family separation. Yet the 1st Native woman to be Cabinet Sec is where Manchin finds unease?” Ocasio-Cortez tweeted.

Manchin’s role as the 50th and toughest-to-nail-down vote in the Democratic caucus has boosted his profile. Pundits have touted him as a new Senate powerbroker and the most powerful member of the evenly divided upper chamber.

WDTV in Bridgeport, W.Va., labeled Manchin last month the “most powerful senator,” while Joshua Green of Bloomberg Businessweek hailed him as a “kingmaker” and The Washington Post wrote he is “the key to Biden’s ambitious climate agenda.”

Manchin kept a relatively low profile during the first few weeks of the new Senate Democratic majority, sticking with his leadership on key votes on the budget resolution, Biden’s top Cabinet picks and Trump’s second impeachment trial.

But he is beginning to assert himself more forcefully as it becomes clear that Republican support will be difficult to muster on certain issues.

The West Virginia senator on Tuesday downplayed talk about him becoming a kingmaker or powerbroker.

“No, there’s nothing about powerbroker. I denounce that completely,” he said.

“I’ll tell you about power. I’ve seen people that have it, abuse it. I’ve seen people that sought it ruin themselves,” he said.

But he also said he’s “seen people that took a moment of time and tried to make a change and a difference,” adding that he hopes to be a lawmaker who works across party lines to make a difference.

Manchin joked the key facts to know about him are “I have three children and 10 grandchildren.”