Other than a two second moment when Warren peaked and led Biden 26.6 to his 26.4, Biden has maintained a substantial lead over all-comers for the entire year in the Democratic primary race. Biden's campaign has survived his lackluster debate performances, gaffes, poor fund-raising reports, his son's role with Burisma, attacks over his past votes, his touchy-feely proclivities, questions about his age and everything else they've thrown at him.
As the front-runner he's been target of the other Democrats candidates on the debate stage and on the campaign trail, yet he's been remarkably steady in the polls for the entire year. In an early debate, Kamala Harris took a swing at Biden when she said she was "that little girl" who benefited from busing, which Biden voted against. She shot up temporarily in the polls and plummeted soon after. It was a road bump for Biden from which he soon recovered when people realized that court-ordered school busing was never popular and they didn't like it either.
Biden hasn't been all that energetic a campaigner. He's not attracting huge crowds, yet he's maintained about a ten point lead in the polls.
Despite their denials, Trump and Republicans clearly see Biden has Trump's number one threat. It's not a coincidence that Trump asked the Ukrainian president to make a televised announcement that Biden was under investigation. It is also no coincidence that Trump has tweeted about Joe Biden and Hunter over 800 times, according to Google search count.
On paper, a 77 year-old presidential candidate should not be this resilient.
Nationally, Joe Biden leads his nearest competitor, Bernie Sanders, 32% to 21%, according to Morning Consult poll of registered voters.
In Mason-Dixon Polling & Strategies polls of two southern swing states, Biden is the only Democrat who beats Trump:
In head-to-head matchups in Florida, Joe Biden is the only candidate who leads Trump.
Biden 47, Trump 45 Biden +2
Trump 49, Sanders 44 Trump +5
Trump 51, Warren 42 Trump +9
Trump 49, Buttigieg 45 Trump +4
In head-to-head matchups in Virginia, Joe Biden is the only candidate who leads Trump.
Biden 49, Trump 45 Biden +4
Sanders 45, Trump 51 Trump +6
Warren 44, Trump 48 Trump +4
Trump 47, Buttigieg 45 Trump +2
Biden may yet lose the nomination, but the reports of Biden's political demise are to date premature. If he's beatable, nobody has managed to figure out his weakness.