WASHINGTON (WLS) -- Ending months of animosity, Bernie Sanders robustly embraced his former rival Hillary Clinton Monday night as a champion for the same economic causes that enlivened his supporters, signaling it was time for them, too, to rally behind the Democratic nominee in the campaign against Republican Donald Trump.
"Any objective observer will conclude that - based on her ideas and her leadership - Hillary Clinton must become the next president of the United States," he declared in a headlining address on the opening night of the Democratic convention.
WATCH: Bernie Sanders says 'Hillary Clinton will make an outstanding president'
President Bill Clinton, watching from the audience, leapt to his feet and applauded, as did most of the delegates filling the convention arena.
Sanders joined a high-wattage line-up of speakers, including first lady Michelle Obama who delivered a forceful, impassioned defense of the Democratic nominee. Mrs. Obama's address all but wiped away earlier tumult in the convention hall that had exposed lingering tensions between Clinton and Sanders supporters.
"I want someone with the proven strength to persevere, someone who knows this job and takes it seriously, someone who understands the issues a president faces are not black and white," Mrs. Obama said. Referring to Trump's penchant for tweeting, she said of the presidency: "It cannot be boiled down to 140 characters."
WATCH: Michelle Obama full Democratic National Convention speech
While Sanders had endorsed Clinton previously, his remarks Monday marked his most vigorous and detailed praise of her qualifications for the presidency. It came at a crucial moment for Clinton's campaign, on the heels of leaked emails suggesting the party had favored the former secretary of state through the primaries despite a vow of neutrality.
Sanders scored the resignation of party chair Debbie Wasserman Schultz, a nemesis in the primaries, but that wasn't enough to quell the anger of supporters. As the convention opened, they still erupted in chants of "Bernie" and booed Clinton the first several times her name was mentioned. Outside the convention hall, several hundred marched down Philadelphia's sweltering streets with signs carrying messages such as "Never Hillary."
By the time Sanders took the stage for the night's closing address, much of the anger had been overshadowed by speeches promoting party unity. Sanders did his part, imploring his supporters to consider a country under Trump's leadership.
"If you don't believe this election is important, if you think you can sit it out, take a moment to think about the Supreme Court justices that Donald Trump would nominate and what that would mean to civil liberties, equal rights and the future of our country," he said.
Sanders spoke just after Massachusetts. Sen. Elizabeth Warren, a favorite of liberals who has emerged as one of the Democrats' toughest critics of Trump.
"Donald Trump has no real plans for jobs, for college kids, for seniors," she said in the keynote address. "No plans to make anything great for anyone except rich guys like Donald Trump."
Mrs. Obama was one of the night's standouts. While she has often avoided overt politics during her nearly eight years in the White House, her frustration with Trump's rise was evident. She warned that the White House couldn't be in the hands of someone with "a thin skin or a tendency to lash out" or someone who tells voters the country can be great again.
"This right now, is the greatest country on earth," she said.
Clinton's campaign hoped the nighttime line-up would overshadow a tumultuous start to the four-day convention. The hacked DNC emails fed the suspicion of Sanders' supporters and sapped Clinton's campaign of some of its energy following a well-received rollout Saturday of her running mate, Virginia Sen. Tim Kaine.
Campaigning in North Carolina, Trump seemed to revel in the Democrats' commotion, telling supporters that Clinton made a mistake by not choosing a more liberal running mate to appease Sanders' base. "Crazy Bernie's going crazy right now," he said.
But in Philadelphia, Delegates waved "Love Trumps Hate" signs and cheered as immigration supporters, gay rights advocates, and labor leaders took the stage.
Comedian-turned-Sen. Al Franken, a Clinton supporter, and actress Sarah Silverman, a Sanders supporter, made a joint appearance to promote party unity.
"I am proud to be part of Bernie's movement," Silverman said as the crowd roared. "And a vital part of that movement is making absolutely sure Hillary Clinton is our next president of the United States."
WATCH: Comedian Sarah Silverman tells Bernie Sanders supporters they're being 'ridiculous'
Trump was a frequent target throughout the night, though the jabs were often more mocking than mean. The tone was a sharp contrast to the Republican convention, where the attacks against Clinton was bitingly personal, including chants of "Lock her up."
WATCH: 11-year-old girl at DNC describes fear of parents' deportation
"I think the overall message that he's delivering is one of unity and one that the people should run government, it shouldn't be about the 1 percent that are in control and have the money," said Illinois Hillary Clinton delegate Larry Rogers, Jr.
"Just as the senator said, it's about us coming together and it's all about not having Trump as a president, and it's a time for us to all come together whether we're Bernie or Hillary, but everyone respects all the work that he did, all the work that we're trying to achieve so that that man Donald Trump will not become president of the United States," said Illinois Hillary Clinton delegate Travis Burke.
"You know we love Bernie, and we love the fact that he spoke up about issues that were important to working people, and we appreciate that," said Illinois Bernie Sanders delegate Theresa Mah.
"I think this was a phenomenal speech, I think it really set our party on the right path heading towards November. I'm so proud of Senator Sanders, he ran an incredible campaign. He lifted the issues we care so much about, and he's negotiated with Secretary Clinton to put together an incredibly progressive vision for our party," said State Rep. and Illinois Bernie Sanders delegate Will Guzzardi (D-39).
ILLINOIS DELEGATION ARRIVES AT DNC
As the arrived and settled into the Democratic National Convention, talk turned from national politics to those of the satte.
"I'm a Democratic governor. You need one of those. You need one of those," Connecticut Gov. Dan Malloy told the delegation.
It took an outsider to make first mention of a topic Illinois Democrats talk about amongst themselves but are reluctant to discuss publicly.
"The election for governor of Illinois is about 30 months away," said U.S. Senator for Illinois Dick Durbin.
Sen. Durbin admitted he's been asked to run in 2018, but when asked if he would do it he said state Democrats should focus now on electing Hillary Clinton president.
"All I can say is I'm focusing on my positive responsibility that the voters gave to me in the last election," Durbin said.
Other potential candidates repeated their focus on the presidential race.
"We have incredible challenges but this week the focus is on national politics," said State Se. Andy Manar (D-Bunker Hill).
"There is no question our number one priority as Democrats is to elect Hillary Clinton president," said Illinois Attorney General Lisa Madigan.
Still, some admitted to being flattered by the attention.
"Obviously I've worked hard over the last 12 years and I hope people have recognized that," said State Sen. Kwame Raoul (D-Chicago).
Wealthy Republican Bruce Rauner, despite the budget stalemate and sagging poll numbers, will reportedly run for a second term. Public sector unions are primed to support a Democrat against him.
"We're never going to beat him dollar for dollar, but we are going to raise enough money that we can defeat him," said Keith Kelleher, SEIU Healthcare.
"You'll find plenty of Illinois Democrats that are anxious to participate in the next governor's election," said State Rep. and state Democratic Party Chairman Michael Madigan.
But Chairman Madigan would not mention names, including his daughter three-term Attorney General Lisa Madigan.
WATCH: New Jersey Senator Cory Booker calls for party unity: "We are called to be a nation of love"
EMAILS HAUNT DNC AT START OF CONVENTION
The controversy over some 19,000 leaked DNC emails threatened to complicate the first day of the convention. The correspondence, posted by WikiLeaks over the weekend, showed top officials at the supposedly neutral DNC favoring Clinton over Sanders in the presidential primaries.
Clinton campaign officials blamed the hack, which is now being investigated by the FBI, on Russian military intelligence agencies. The campaign also accused Moscow of trying to meddle in the U.S. election and help Trump, who has said he might not necessarily defend NATO allies if they are attacked by Russia.
Trump dismissed the suggestion in a tweet: "The joke in town is that Russia leaked the disastrous DNC emails, which should never have been written (stupid), because Putin likes me."
A cybersecurity firm the Democrats employed found traces of at least two sophisticated hacking groups on their network - both of which have ties to the Russian government. Those hackers took at least a year's worth of detailed chats, emails and research on Trump, according to a person knowledgeable of the breach who wasn't authorized to speak publicly about the matter.
The Associated Press contributed to this report.