WASHINGTON — In the end, the most influential politician of 2020 might be the one who has been the most silent.

With Bernie Sanders exiting the race and Joe Biden taking on the mantle of presumptive nominee, the man who hovered quietly over the race for more than a year, Barack Obama, will soon return to the political fray.

Obama wanted Sanders to have the day to himself, so he refrained from speaking (or tweeting) publicly on Wednesday. But Obama had always said his role in the primaries would be to unite the party when it’s over, and he’s been in close contact with both campaigns as the pandemic both froze the race without a clear victor and also made it more obvious that Biden would eventually prevail.

“Over the last few weeks, he’s had multiple conversations with candidates, including Sen. Sanders, about how to best position the Democratic Party to win in November,” said a source familiar with those calls. “While the content of those conversations remain private, there was always agreement that winning in the fall was paramount.”

“A very good day!” one Obama adviser wrote when I asked about Sanders dropping out.

Obama played a role in nudging things in Biden’s direction at the crucial moment when the Biden team was organizing former candidates to coalesce around Biden.

Obama mostly stuck to his pledge not to interfere in the race, but in 2019 there was one enormously important exception. In mid-November at a Democratic donor event he weighed in forcefully on the left vs. centrist argument that was then dominating the race. He warned Democratic candidates not to confuse actual voters with “left-leaning Twitter feeds.” He said that voters “don’t want to see crazy stuff,” that America is “less revolutionary than it is interested in improvement,” and that politicians pushing immigration policies that deny the existence of a border “may be in for a rude shock.”

If there was a casualty of Obama’s comments, it might have been Elizabeth Warren, who lost her lead in both Iowa and New Hampshire (to Pete Buttigieg) that same week and never regained it. Obama’s warning about the electoral consequences of leftism may have been the most important moment of the 2019 pre-primary season. At the time of those comments, several of Obama’s closest advisers, who all opposed Sanders, told me in interviews that Sanders was a spent force, a mistake that many observers made at the time. Obama was publicly silent for the remainder of the campaign. But one of his closest advisers issued a warning: “If Bernie were running away with it, I think maybe we would all have to say something.”

As the race narrowed to Biden and Sanders, interest among pro-Biden Democrats for Obama to speak up spiked and the political press was on the hunt for any indications of Obama choosing sides. Obama had a delicate task. Everyone knew whom he preferred, and yet he could not be seen as helping organize the massive party-wide show of force in favor of Biden that emerged from South Carolina through Super Tuesday. Obama’s aides forcefully reiterated that he was scrupulously not intervening.

But some of his aides now concede that behind the scenes Obama played a role in nudging things in Biden’s direction at the crucial moment when the Biden team was organizing former candidates to coalesce around Biden.

“I know he did a few things,” said one longtime close adviser to Obama. “He was talking to Biden regularly in that period. I don’t know exactly what he said, but you can speculate! It’s noteworthy that he called Klobuchar and the others right when they got out.”

A person with knowledge of Obama’s conversation with Buttigieg after the former Indiana mayor exited the race explained it this way: “Obama talked to Pete the night that Pete dropped out. When Pete told Obama that he was 99.9 percent of the way there in terms of endorsing Biden, I would say that Obama was encouraging. But I would also say that Obama was very careful not to be seen as putting a thumb on the scale. He and the people close to him are very careful about the optics — the 2016-style optics. Sanders and his supporters had reason to believe the party put the thumb on the scale for Hillary in 2016 and he wanted to avoid that. Obama wasn’t the driving force, but he was encouraging of people who had those instincts to rally around Biden. But he was very cautious and discreet in how he operated.”

A Democratic strategist added, “The truth is, he’d rather be on David Geffen’s yacht than dealing with internal Democratic party bullshit.”

Detached from the political fray?

That’s a little unfair, but it plays into a popular stereotype of Obama during the Trump era as too detached from the political fray. But Obama has had a fairly consistent strategy of husbanding his political capital and only speaking publicly when he was sure it would have some impact (as it seemed to in November) and laying back from pure electoral politics until the final stretch of the campaign (as in 2018).

“[Sanders’ exit from the race] frees up Obama to live up to what he said — that he wasn’t going to put his thumb on the scale until there was a nominee,” said the longtime Obama adviser. “Now he’ll do anything the party and the nominee want to help win the election.”

Obama will soon make the case for Biden that Biden has had trouble making himself. “He will come out and make the point that Biden is the man for the times, that he has the experience and judgment to lead the country,” the adviser said. “He’ll make an obvious comparison to Trump but without saying too much about Trump: ‘This is a moment where we need someone like Biden.’ It’s the contrast that Biden has been trying to make — though I’m not sure how successfully — with his streaming from his basement.”

The other area where Obamaworld believes — perhaps naively — that the former president will have a role is in helping Biden with younger voters. Just as Biden once helped Obama win over older voters worried he was too young and too inexperienced, Obama will now try to help Biden win over younger, more liberal voters who think he’s too old and too experienced.

It will be an interesting test for Obama. In the online Sanders universe, Obama is often derided as a neoliberal (and much worse) and his administration is seen as a failure. Obama may find that young progressives view him — rightly or not — as a boomer from a bygone era of diminished ambitions.

“I would try to use Obama as a bridge to the progressive community,” said the adviser. “Because of the 'It factor' that Obama still has, I wouldn’t discount the possibility of Obama being able to rekindle that among younger voters.”

Obama has survived one crucial test. A presidential primary is often a referendum on the party’s last president. And in the 2020 Democratic primaries, Obama — or at least Obamaism — prevailed.