Sen. Bernie Sanders Bernie SandersKenosha will be a good bellwether in 2020 Biden's fiscal program: What is the likely market impact? McConnell accuses Democrats of sowing division by 'downplaying progress' on election security MORE’s endorsement of Joe Biden Joe BidenSenate Republicans face tough decision on replacing Ginsburg What Senate Republicans have said about election-year Supreme Court vacancies Biden says Ginsburg successor should be picked by candidate who wins on Nov. 3 MORE on Monday gave the former vice president something Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE never had when it came to unifying the Democratic Party: Plenty of time.

Democrats have fretted since their race began with two dozen candidates that they would have a hard time unifying around a single nominee, and that a divisive primary would hurt their eventual standard-bearer.

Their nightmare since the beginning of the race has been that a splintered Democratic Party would end up costing them another election to President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE.

ADVERTISEMENT

But the endorsement by Sanders — who made a surprise appearance on Biden’s livecast Monday afternoon — cleared the way for the former vice president to begin bringing the party together. And it happened in the middle of April.

“2020 will be more unifying than 2016 because of time being given to Vice President Biden to consolidate the party,” said Michael Trujillo, a Democratic strategist who worked on Clinton’s 2008 presidential campaign.

The moment helped calm the nerves of jittery Democrats, who have been having deja vu when it comes to Sanders, a democratic socialist from Vermont who caucuses with Senate Democrats but has an "I" next to his name and state.

“We need you in the White House and I will do all that I can to see that that happens, Joe,” Sanders said during the appearance.

It took Sanders just five days to endorse Biden after he announced the suspension of his campaign last week.

Some Democrats were quick to point out that Sanders didn’t officially endorse Clinton until July 12 — 36 days after he suspended his campaign.

ADVERTISEMENT

“Democrats learned a vital lesson from the 2016 election: If you don't unite, you lose,” said former Rep. Steve Israel Steven (Steve) J. IsraelThe Hill's Morning Report - Presented by Facebook - Trump, Biden intensify battleground focus as 2020 race tightens Biden allies express confidence as convention begins The Hill's Campaign Report: Biden closes in on vice presidential pick MORE (D-N.Y.), who also led the Democratic Congressional Campaign Committee.

One major Democratic donor said the move by Sanders gives Biden a significant advantage over Clinton.

"At the same time last cycle, we were still very much in the thick of things,” the donor said. “Biden definitely has a major advantage."

“Unity for us starts in April,” the donor added. “Not July. That’s huge.”

Since the Democratic National Convention has been pushed back to August, Democratic strategist Joel Payne, who served as the director of African American paid media and advertising on Clinton’s 2016 campaign, said Biden now has a 12-week head start on fundraising and organizing.

It also gives him more time to get “the Bernie wing comfortable,” he said.

“He needs time to mend fences and get people on the same page,” Payne said. “And the more time you have the better.”

Still, while Biden appeared ahead of the game in terms of time, there were still signs of trouble bringing even Sanders campaign aides aboard with his endorsement.

“With the utmost respect for Bernie Sanders, who is an incredible human being & a genuine inspiration, I don’t endorse Joe Biden,” Briahna Joy Gray, who served as Sanders’s national press secretary, wrote on Twitter.

“I supported Bernie Sanders because he backed ideas like #MedicareForAll, cancelling ALL student debt, & a wealth tax. Biden supports none of those.”

National Democrats are also looking for more help from Sanders.

Philippe Reines, who served as a longtime adviser to Clinton, said “there’s a lot more work to do and he has to put his money where his mouth is.”

“He needs to drop the hammer on any supporter — especially those associated with his campaign — who regurgitates right-wing attacks on Biden,” Reines said. “That’s still happening so he needs to go medieval on anyone who does so, every time, without fail. The fish supports from the head as much as rots from the head.”

Still, while Biden has the advantage of time, political observers say the coronavirus pandemic is almost certain to throw another obstacle into the mix.

“After all the hoopla, he solidified his hold on the primary earlier than Clinton and has a party more unified because of a disliked incumbent. All of that is true,” said Julian Zelizer, a professor of history and public affairs at Princeton University. “But — and a big but— this is an election unlike any other."

Zelizer said Biden won’t be able to do traditional campaigning that helps promote candidates including rallies, town halls and extensive media interviews.

“The election itself will have less coverage than usual because of the pandemic, and it’s possible this is an extremely low turnout election because of social distancing,” he said. “So even though on paper he is in great shape, the nature of this campaign presents immense challenges.”