The more incoming fire Joe Biden takes, the more he's gluing his candidacy to the Obama legacy.

The former vice president has from the start built his campaign brand around the work of the administration he helped lead. But it's a theme he's hitting even harder, as his Democratic presidential primary rivals call him out for his past stances on civil rights issues and his less-than-tactful comments in recent days on race and other sensitive matters.

“Barack was a president our kids not only could, but did, look up to,” Biden touted on Friday, namedropping his former running mate during a Chicago speech before Jesse Jackson’s Rainbow PUSH Coalition.

This was after Biden repeatedly invoked former President Barack Obama during last Thursday’s debate when discussing issues including health care, immigration and climate change -- taking a stand against those pushing "Medicare-for-all" by insisting that ObamaCare is the best building block for health care reform.

“The fact of the matter is that the quickest, fastest way to do it is build on ObamaCare, to build on what we did,” Biden said at the debate, while at another point boasting about Obama's climate change record, calling him "the first man to bring together the entire world, 196 nations, to commit to deal with climate change."

Last month, Biden’s Twitter account even shared an image of “Joe” and “Barack” friendship bracelets, a throwback to when he first posted the picture in honor of Obama’s 55th birthday in 2016.

“Happy #BestFriendsDay to my friend, @BarackObama,” the tweet said.

Yet as Biden runs as the champion and defender of the Obama legacy, it's been radio silence from Obama himself. The only word was a reported statement from spokesperson Katie Hill, which said, “President Obama has long said that selecting Joe Biden as his running mate in 2008 was one of the best decisions he ever made."

This, however, fell short of an endorsement. According to Biden, that was at his own request.

“I asked President Obama not to endorse,” Biden said back in April.

The popular 44th president is surely mindful not to put his thumb on the scale in the heated and historically crowded 2020 presidential primary battle.

But President Trump is eager to suggest Obama is holding back with Biden. "Then he goes and lies and says, 'I asked the president not to endorse me.' Give me a break," Trump told The Hill in a June interview.

Meanwhile, Obama's former aides have not been shy in raising questions about Biden's campaign and message.

Alyssa Mastromonaco, who served as Obama’s deputy chief of staff, all but called Biden naive over his hopes to work with Republican lawmakers.

“Maybe you can shame people,” she tweeted. “You can’t shame McConnell.” Mastromonaco suggested a path to bipartisanship would be ideal but Biden’s plan “isn’t that path.”

And when Trump described Biden as “weak mentally,” Obama's former top strategist David Axelrod -- who questioned Biden's "steadiness" about an abortion policy flip-flop -- warned that Biden “has sort of played into the caricature.”

Axelrod also raised concerns about Biden after Thursday's debate that saw a heated exchange between Biden and Sen. Kamala Harris, D-Calif., over the former veep's comments about working with segregationist senators and his past opposition to federally mandated busing to integrate schools.

Axelrod described Biden as “confused” and suggested he looked like “part of the past rather than the future.”

Biden and his aides have adamantly defended his record against Harris and other critics.

“If you want to put Vice President Biden’s record on civil rights up against anybody else on that stage, he’ll stand the test of time,” adviser Symone Sanders told reporters Thursday night.

Biden has only run into more trouble since then, including with comments at the Chicago event.

“That kid wearing a hoodie may very well be the next poet laureate and not a gangbanger," Biden said, making a rhetorical point during remarks for the Rainbow PUSH Coalition event.

“This isn’t about a hoodie," Sen. Cory Booker, D-N.J., wrote on Twitter. "It’s about a culture that sees a problem with a kid wearing a hoodie in the first place. Our nominee needs to have the language to talk about race in a far more constructive way.”

Then at a Pride weekend fundraiser, Biden tried to tout how far Americans have come in a short amount of time by talking about how just five years ago it was acceptable to make “fun of a gay waiter.” The Seattle audience did not appreciate the remark.

Earlier in the campaign, Axelrod told the New York Times that Biden’s campaign was doing a good job of limiting public gaffes, but warned, “the pace is going to quicken as the race goes on and you can’t keep him in candidate protection program.”