In a valedictory speech Monday night at the Democratic National Convention, Sen. Bernie Sanders (I-Vt.) urged his most passionate supporters to close ranks behind presumptive Democratic presidential nominee Hillary Clinton. 

"Any objective observer will conclude that, based on her ideas and her leadership, Hillary Clinton must become the next president of the United States," Sanders told a capacity crowd at the Wells Fargo Center in Philadelphia. "The choice is not even close."

It was a message some Sanderistas still weren't ready to hear. Throughout the first night of the Democratic Party confab — even during their candidate's primetime address — a small number of them jeered Clinton whenever her name was uttered. 

Sanders acknowledged their heartache and confessed that he shared it.

"I understand that many people here in this convention hall and around the country are disappointed about the final results of the nominating process," he said. "I think it's fair to say that no one is more disappointed than I. But to all of our supporters, here and around the country, I hope you take enormous pride in the historical accomplishments we have achieved."

It appeared that they did. The arena erupted in applause late Monday when the senator took the stage. Sanders and Clinton delegates alike gave him an extended standing ovation, holding aloft light blue signs featuring his first name and the bird that came to symbolize his campaign. 

When he hailed his 1,846 pledged delegates, one of them — recent South Burlington High School graduate Aster O'Leary — jumped to her feet to cheer. All around O'Leary in the Vermont stands, Sanders' neighbors basked in the glow of his remarkable run. 

"It's incredible. Unreal," said Noah Detzer, a delegate from White River Junction. "I've followed this from the day that he announced. This is kind of the end, which is sad, but every step of the way I've been so blown away by him as a candidate. And I'm just so privileged to be part of this movement."

Sen. Patrick Leahy (D-Vt.) and Congressman Peter Welch (D-Vt.) sat nearby Detzer and applauded their congressional colleague. 

"We've heard a lot of it before, but he pointed out how close he and Hillary are on the issues," said Leahy, a Clinton delegate who has served with Sanders for more than 25 years. "I think it's a good start for the campaign ... He could not have made [Republican nominee] Donald Trump very happy."

Welch, one of Sanders' few congressional endorsers, called Sanders' speech "beyond magnanimous."

"It was really a statesmanlike address, explaining to his supporters that there's a lot of heartbreak in politics, but you've gotta go on and take the next step," Welch said. "So I thought it was just a measure of his character that he did this tonight."

Earlier Monday at the Philadelphia Convention Center, Sanders delegates had booed their candidate when he called on them to vote for Clinton. They continued their protest into the evening, interrupting even Sanders supporters, such as Sen. Jeff Merkley (D-Ore.). After Congressman Elijah Cummings (D-Md.) called the Democrats "a party of unity — and not division," a chorus of Sanderistas proved him wrong.

"No T-P-P!" they chanted, referring to the proposed Trans-Pacific Partnership trade deal.

Even before he appeared onstage, Sanders sought to calm his partisans. In an email to delegates, he wrote that "everyone is frustrated" — particularly by recently revealed Democratic National Committee emails showing that party officials had favored Clinton's campaign over his. But he urged his supporters to refrain from "protest or demonstration on the convention floor."

"Our credibility as a movement will be damaged by booing, turning of backs, walking out or other similar displays," he wrote. "That's what the corporate media wants. That's what Donald Trump wants. But that's not what will expand the progressive movement in this country."

A trio of entertainers seemed to help his cause.

Sen. Al Franken (D-Minn.), a Clinton supporter, and fellow comedian Sarah Silverman, a Sanders supporter, appeared onstage together shortly before 9 p.m. and made an appeal for unity. Calling the Democratic primary "exemplary" for avoiding "name-calling," Silverman said she would "vote for Hillary with gusto."

"I am proud to be a part of Bernie's movement — and a vital part of that movement is making sure Hillary Clinton is the next president of the United States," she said, adding later, "Can I just say to the 'Bernie or Bust' people: You're being ridiculous."

The two were followed to the stage by the singer Paul Simon, whose anthem, "America," served as the soundtrack to Sanders' most memorable campaign commercial. The artist chose a different song to perform Monday night — perhaps a more fitting one, given the divisions on display: "Bridge Over Troubled Water." 

Rounding out the night were speeches from three stars of the Democratic Party: Sen. Cory Booker (D-N.J.), Sen. Elizabeth Warren (D-Mass.) and seemingly the only speaker more popular in the arena than Sanders, First Lady Michelle Obama. 

But it was Sanders who got the last word. 

"Hillary Clinton will make an outstanding president," he said as he concluded his address. "And I am proud to stand with her here tonight."