By Agence France-Presse
"Some say Democrats don't want to hear about unity. That they are angry -- and the angrier you are, the better," Biden will say at a campaign rally in Philadelphia, according to speech excerpts.
"I don't believe it," he will tell the crowd, adding that he is running for president to offer Democrats and Republicans alike a "different path" towards unity.
"If the American people want a president to add to our division, to lead with a clenched fist, closed hand and a hard heart, to demonize the opponents and spew hatred, they don't need me. They already have a president who does just that."
Biden, 76, sits atop the pack of 2020 contenders, relishing his prime position.
No one knows whether the man who served as number two to popular Democratic president Barack Obama for eight years will run away with this contest -- his third White House bid in as many decades -- or fade out in the months-long test of political skill and stamina to come.
But the former longtime senator and lion of the Democratic Party is gearing up for what is certain to be a titanic battle against Trump.
After a month of modest events at union halls and pizza joints in early-voting states like Iowa, Biden is counting on making a splash at a rally in Philadelphia, the largest city in must-win Pennsylvania, a state Trump snatched from Democrats in 2016.
He has made Philadelphia his campaign headquarters, in a sign of the importance he places on winning back the state for his party in 2020.
Biden will acknowledge that the country fell short of its ideals early on.
"Equality. Equity. Fairness. America didn't live up to that promise for most of its people, for people of color, for women," he will say.
The kickoff is near the Philadelphia art museum steps immortalized by the scrappy boxer's run in the movie "Rocky."
Biden was born and raised in Pennsylvania, and the rally is a nod to his modest roots.
But far from being the underdog, Biden is looking to cement his status as the man to beat, the blue-collar voter whisperer who is best positioned to defeat Trump.
And while his delayed race entry drew criticism that he might not be ready to mount an energized campaign, the slow-and-steady strategy appears to be paying off.
Polls give Biden a growing lead over the 22 other hopefuls.
The latest RealClearPolitics aggregate puts him at 39.1 percent support, more than double the 16.4 percent of his nearest rival, liberal Senator Bernie Sanders.
No one else is in double digits.
After a deeply divisive 2016 race, Democratic voters may be looking for an antidote to Trump, the brash politically inexperienced billionaire.
"What matters to them at the moment is a safe choice, a known entity," Lara Brown, director of George Washington University's Graduate School of Political Management, told AFP.
Biden's celebrity rivals that of Trump. But as voters start paying more attention, Biden -- who to date has campaigned mostly in broad strokes -- will be under pressure to flesh out positions on everything from health care and wages to immigration.
Biden's dominance has already changed the race's dynamic, with its early stars like senators Sanders, Kamala Harris and Elizabeth Warren forced to play catch up, and leveling criticism at the frontrunner.
They are expected to ramp up criticism of Biden as the embodiment of the Washington establishment.
Several rivals are from a newer generation, putting them at odds with the old-school Biden.
And while candidates are honing their messages at town halls and meet-and-greets, Biden has opted for more protected environments.
"Let's see what happens when he's taking questions that haven't been vetted," Brown said, noting Biden has faced criticism from liberal groups following reports he was planning to unveil a "middle ground" approach to tackling climate change.
Biden has aligned himself closely with Obama, drawing major support from African American voters.
He also styles himself, like Trump, as an ardent defender of working class Americans, someone who can win back the Midwestern white, male blue-collar voters who went for the Republican in 2016.
Trump has insisted he does not see Biden "as a threat."
But he has bestowed a harsh nickname on his rival -- "Sleepy Joe" -- and has scheduled a campaign rally for Monday in northern Pennsylvania, just 50 miles (80 kilometers) from Scranton, where Biden was born and raised.