WILMINGTON, Del. — When Joe Biden released economic recommendations two months ago, they included a few ideas that worried some powerful bankers: allowing banking at the post office, for example, and having the Federal Reserve guarantee all Americans a bank account.

But in private calls with Wall Street leaders, the Biden campaign made it clear those proposals would not be central to Biden’s agenda.

“They basically said, ‘Listen, this is just an exercise to keep the Warren people happy, and don’t read too much into it,’ ” said one investment banker, referring to liberal supporters of Sen. Elizabeth Warren (D-Mass.). The banker, who spoke on the condition of anonymity to describe private talks, said that message was conveyed on multiple calls.

This reluctance to be pinned down on policy details is central to Biden’s campaign, which has focused on a pledge to “restore the soul of the nation” rather than any particular legislative holy grail. While Biden has issued a raft of proposals, he’s often taken an all-things-to-all-people approach, sometimes making strong public declarations while relying on aides to soothe critics behind the scenes.

That strategy, reflecting a decades-long career in which Biden has seen himself more as mediator than ideologue, has helped him unify the party’s liberal and moderate wings behind the shared goal of defeating President Trump. But it also is laying the groundwork for bitter internal battles, should Biden win the presidency, on topics from race to climate to trade, while Wall Street leaders plan to have their way with a president many expect to be unusually susceptible to outside pressure.

“His gut reaction is to legislate; he’s been a legislator,” said Leon Panetta, who worked with Biden as Barack Obama’s defense secretary. “He’s going to try to build — or test — bipartisanship to see if he can rebuild that in the Congress and see whether that takes him anywhere.” He added, “A lot of presidents walk into that office with all kinds of ideas about the great things they are going to accomplish, only to run into the wall of reality.”

The Biden campaign said the economic recommendations were produced jointly by supporters of Biden and Sen. Bernie Sanders (I-Vt.) and were never intended as official policy. “The Biden-Sanders task forces made recommendations to Vice President Biden and to the [Democratic] platform drafting committee,” said campaign spokesman TJ Ducklo. “This anonymous source appears to be confused and uninformed about this very basic distinction.”

But the tension in such strategic flexibility was on display last week when Biden, speaking in Pittsburgh, rejected Trump’s assertion that he would ban fracking, a way of extracting fuel from underground rock. Environmentalists criticize fracking as highly risky, and in the primary, Biden had highlighted his desire to curtail it — but it provides numerous jobs in Pennsylvania.

Biden has long had a nose for his party’s shifting center, according to officials who have worked with him. When the Democrats moved right — embracing tough-on-crime measures and opposing government funding for abortion — Biden was there. When the party recently veered left — dropping those positions and emphasizing racial justice and gender equity — Biden embraced those priorities.

While Trump in 2016 loudly promised to end illegal immigration and Obama in 2008 passionately pledged health care for all, Biden’s central promise in this campaign is simply to restore basic decency.

In the meantime, he is giving all sides something to hold on to. Biden has suggested he would emulate big-spending Franklin D. Roosevelt, but aides have also said he’s deeply mindful of the federal deficit. He’s embraced the symbolism of the Black Lives Matter movement, but he rejects some of its highest-profile demands.

Biden’s supporters portray his flexibility as a virtue.

“He’s not afraid to move off of his position, if that makes sense,” said Lee Saunders, president of the American Federation of State, County and Municipal Employees, one of the country’s largest unions. “Biden approaches issues with a very open mind. He is someone who is not afraid to listen to different perspectives, and to change.”

This results, in part, from Biden’s more than three decades in the Senate, where bold ideas are often hemmed by political reality. Most Senate bills need at least 60 votes to pass, which forces bipartisan compromise — and is the reason many liberals want to get rid of the filibuster if Democrats retake the Senate.

Andrew Yang, who ran against Biden in the Democratic presidential primary, suggested that once Biden adopts a position, he gives it a stamp of acceptability. “People regard him as reasonable, and he’s been very moderate for decades of public life,” Yang said in an interview. “So he can define the center, or redefine it, very quickly.”

Biden’s campaign says he is doing just what a candidate should — pushing broad ideas while leaving room to negotiate the details.

Jake Sullivan, a top Biden policy aide, noted that in the primary, Biden held fast to his proposal for a public health-care option, while rivals yielded to pressure from liberal groups to embrace a far more sweeping Medicare-for-all plan.

“There’s no doubt that the vice president is a coalition builder and wants to put together a broad base of support for programs so that it’s sustainable way over time,” Sullivan said. But that doesn’t mean Biden doesn’t have strong principles, he added: “There’s also no doubt that Joe Biden has a very clear sense of where he wants things to go.”

For now, some liberals are cautiously pleased Biden has taken steps in their direction. But others, including some Black Lives Matter activists, are pressing for more concrete commitments, worried they will prove elusive once Biden is elected.

All these activists fully expect they’ll have to fight to hold Biden to his promises after Election Day. Sen. Bernie Sanders (I-Vt.) told SiriusXM recently that if Democrats win Congress and the White House, “we will be damn sure that he will follow through on the proposals that he is supporting right now.” He cited, for example, Biden’s endorsement of three months of paid family and medical leave and an expansion of child care.

After Biden locked up the Democratic nomination in the spring, his supporters and Sanders’s backers formed task forces aimed at merging the two candidates’ positions. Sanders supporters found they could win significant concessions on policy, as long as those measures could be framed as fitting within Biden’s broad public statements.

“We knew we weren’t going to get Medicare-for-all,” said Rep. Pramila Jayapal (D-Wash.). “The question then for me was: How do we get some foundational pieces of Medicare-for-all, even if the words ‘Medicare-for-all’ aren’t there?”

Biden’s team agreed, for example, that low-income Americans would be automatically enrolled in Biden’s public option and that Medicare, not a private company, would run it — significant concessions that nonetheless fell under Biden’s original framing.

“A good tell about how Biden would operate is, there’s room for him to run as long as he doesn’t feel like he’s overturning his brand of moderation,” said one liberal who negotiated with Biden’s team.

Still, in a sign of the potential for post-election clashes, the Biden team views the task forces’ ideas as merely recommendations, while many Sanders supporters consider them binding.

Biden’s record of negotiating tricky political terrain is a long one. A few years after he entered the Senate in 1973, the Democratic Party began a steady shift to the right, as many in the party concluded the liberal enthusiasms of the 1960s were alienating a critical mass of voters.

In tune with that shift, Biden opposed the busing of students to fight de facto segregation, embraced tough-on-crime measures and campaigned as a deficit hawk, even as he adopted liberal positions in other areas.

That early instinct for the middle has never left him, though he is regularly adjusting it. Former senator Ted Kaufman (D-Del.), a longtime ally, said in August, for example, that a President Biden would be financially prudent, given the recent explosion in the federal deficit.

“I do not think there’ll be a big increase in federal spending because I think basically when we get in, the pantry is going to be bare,” Kaufman said at a breakfast hosted by the Wall Street Journal. “We’re going to have limited funds to do what we’re going to do.”

But in recognition that circumstances have changed because of the pandemic and social upheaval, Biden’s campaign quickly walked back that statement. Campaign spokesman Andrew Bates instead sought to distinguish between Biden’s support for short-term spending to fight the pandemic’s effects and the economic collapse and longer-term expenditures that would reshape government’s role.

Yet the difference is not always obvious. Activists have begun shaping their proposals to fit within what one called Biden’s “covid perimeter,” justifying them in terms of fighting the pandemic’s impact even if they also have other purposes.

Once the government starts offering a service like health coverage or financial aid, the thinking goes, it is hard to withdraw it. So programs launched to fight ­covid-19 could become a permanent part of the social fabric.

Some Democrats maintain that if Biden triumphs, intraparty fights will be relatively restrained. Winning the White House has a way of quelling rather than exacerbating internal bickering, said Matt Bennett, a co-founder of Third Way, a center-left think tank.

“I don’t think there is as much division as some of the louder voices on the left may think,” said Bennett, a veteran of the Clinton White House. “They’re going to be louder than we are about their discontent because that’s just how they are. They will be frustrated sometimes, and we will be frustrated sometimes.”