Pete Buttigieg’s presidential campaign has spent the past few weeks subtly or overtly attacking every major fellow Democratic candidate in the presidential race. Save one.

The South Bend mayor has left Joe Biden off his target list, content to see the former vice president fall on his own, after which—the thinking goes—his supporters will flock to a similarly mild-mannered moderate candidate; namely, Mayor Pete.

The strategy is a high-risk one for Buttigieg, even as he continues to stockpile resources that prepare him well for the final stages of the pre-voting phase of the primary; his campaign announced Tuesday that it had raised $19.1 million in the third quarter. Indeed, the Democrat’s attacks on his fellow rivals have begun to anger fellow party members, who view it all as a massive showcase of presumption from a 37-year-old mayor.

“He’s trying to get some splash,” an adviser to a top rival campaign said. “How do you get some splash? You go after the person who has the juice.”

A Buttigieg campaign official swears they’re “not even trying to subtweet other people” and only want to draw policy contrasts between more progressive rivals, which is why Biden is not currently a target. But officials in multiple 2020 campaigns contacted by The Daily Beast said they’ve felt and noticed the mayor’s slights in recent weeks, arguing he’s taking veiled swipes to make up for a polling downturn.

“Pete’s calculation is always ‘How can I offend the fewest voters?’ so it’s not surprising to see him attack candidates who dare to have an original idea,” said another campaign official for a separate candidate.

A third candidate’s aide gave the grimmest possible explanation: “It does seem a little desperate.”

Hovering slightly above 5 percent average in Real Clear Politics’ national polling index, Buttigieg remains solidly within the top five Democratic contenders. But he’s well behind Biden, who earns around 27 percent in the index, and is still a ways away from progressive rivals Sen. Elizabeth Warren (D-MA) and Sen. Bernie Sanders (I-VT), who earn 23 percent and nearly 18 percent, respectively.

In the past several weeks, Buttigieg has attempted to narrow that gap.

A Harvard graduate often lauded for his bookish thoughtfulness, he was eager to draw contrasts between Warren, the former law professor from the same school, and Sanders, the self-avowed democratic socialist, over health care.

“She and I are after the same goals,” Buttigieg said to Bloomberg News about Warren, who raised $19.1 million in the second quarter but has not yet released her third-quarter haul. “But her pitch has a lot more to do with fighting—she’s more interested in the fighting part of it. I’m more interested in outcomes.”

On Tuesday, Democrats rushed to Warren’s defense, pointing largely to her success conceiving the Consumer Financial Protection Bureau.

“Outcomes? Elizabeth Warren created the CFPB and has been elected twice by millions of voters. Pete has won elections with numbers that rival student body presidents,” progressive strategist Rebecca Katz tweeted.

“Pete’s posturing as more focused on outcomes than a woman who conceived of an entire federal agency, got it written into law, and built is tiresome,” Adam Jentleson, who previously served as a top aide to former Senate Majority Leader Harry Reid, wrote on Twitter. “Pete was on OK mayor of a small town (depending on who you ask) and could learn a lot from Warren if he had an ounce of humility.”

It wasn’t the first time Buttigieg jabbed Warren in recent weeks. In an appearance on The Late Show, the Massachusetts Democrat did not directly answer Stephen Colbert’s question about whether middle-class taxes would increase under her health-care plan. Eyeing that, Buttiegig pounced.

“Sen. Warren is known for being straightforward and was extremely evasive when asked that question, and we’ve seen that repeatedly,” Buttigieg said in an interview on CNN shortly after. “I think that if you are proud of your plan and it’s the right plan, you should defend it in straightforward terms,” he added.

An official from Buttigieg’s campaign told The Daily Beast they were most interested in drawing contrasts with both Warren and Sanders on that specific policy concentration, pointing to the popularity of the mayor’s plan and his more moderate credentials.

“It’s just about pointing out their differences on health care,” the official said. “He’s not going to make personal attacks.”

Still, the progressive senators are not the only presidential contenders Buttigieg has singled out. He has also launched thinly veiled attacks on multiple candidates polling lower nationally.

More recently, Buttigieg’s husband, Chasten, launched a slight attack at Cory Booker (D-NJ)—a claim his campaign denies—in a fundraising appeal before the third-quarter deadline in which he touted the campaign’s progress but noted, “the pressure is on.”

“And by pressure, I don’t mean the campaign will shut down if we don’t raise $1.5 million by 11:59 p.m. tonight,” Chasten wrote in his note.

The line–referencing a highly specific dollar goal by a precise time of the day–appeared to be a swipe at Booker, whose campaign reported raising over $6 million in the third quarter, amassing $2.1 million in the last 10 days of September. Booker campaign manager Addisu Demissie told reporters last month that if they didn’t raise an addition $1.7 million by Sept. 30, they did not have a “legitimate long-term path forward” to continue competing in the 2020 contest.

A separate attack came as Buttigieg sought to create a contrast with another contender who once received similar rising-star status: former Rep. Beto O’Rourke (D-TX). After O’Rourke earned applause during the third Democratic debate for declaring, “hell yes, we’re going to take your AR-15, your AK-47,” Buttigieg argued that the Texas Democrat was only helping the other side.

Trump and Senate Majority Leader Mitch McConnell are “at least are pretending to be open to reforms,” said Buttigieg, who received pushback from O’Rourke himself. “We know we have a moment on our hands. Let’s make the most of it and get these things done.”

As the digs have piled up, so has the annoyance of Buttigieg’s primary opponents. Making a case to voters in Iowa, the South Bend mayor once again leaned on his Washington-outsider status while launching a vague dig at up to three possible rivals, saying that politics is about more than “the daily drama of who looked good in a committee meeting.”

Sens. Kamala Harris (D-CA), Amy Klobuchar (D-MN), and Booker each sit on the Senate Judiciary Committee. But it was Harris who received disproportionate praise for her grilling of Attorney General William Barr, a clip her campaign has recently resurfaced to get her back into the national conversation.

When presented with the possibility that Buttigieg’s comment was a dig at Harris, one prominent backer of the California Democrat threw some shade back.

“If it is [an attack on Harris], he is losing,” the ally said.