In a recent email exchange with a wealthy prospective donor, a top fundraiser for Democratic presidential candidate Pete Buttigieg made an offer that was unusually blunt — even by modern pay-to-play standards.

What they're saying: "If you want to get on the campaign's radar now before he is flooded with donations after winning Iowa and New Hampshire, you can use the link below for donations," the fundraiser, H.K. Park, wrote in an email to the donor, which was reviewed by Axios.

The Buttigieg campaign lists Park on its website as one of its top fundraisers — those who have raised at least $25,000 for the campaign.

Why it matters: Brendan Fischer at the campaign finance watchdog the Campaign Legal Center said the Buttigieg fundraiser's pitch "is an example of a campaign offering potential donors an opportunity to buy influence."

"It's rare that the public has an opportunity to see it in writing," Fischer added, "but this is not the only campaign that's offering big donors the opportunity to get on the radar of the candidate in exchange for large contributions."

The revelation comes days after Democratic presidential rival Elizabeth Warren went after Buttigieg for raising money from billionaires in a "wine cave."

The prospective donor was also disturbed by the solicitation. "It's very telling and concerning that one of the campaign's major bundlers would talk like that," said the donor, who asked not to be named.

"What would this suggest about the way he's going to interact with Silicon Valley if the implication is pay-for-play?"

"If that's the way he's operating," the donor added, "it's in the public interest for people to know what's being said."

Sean Savett, a Buttigieg campaign spokesperson responded: "The campaign did not see or authorize the language in this email. But it is ridiculous to interpret it as anything more than asking potential supporters who may be interested in Pete to join our campaign before caucusing and voting begins."

"We are proud to have more than 700,000 donors who have already donated to our campaign, and the only promise any donor will ever get from Pete is that he will use their donations to defeat Donald Trump."

The big picture: Buttigieg's fundraising tactics have emerged as a major issue in the 2020 Democratic primary. Left-wing rivals of the South Bend mayor, Warren and Bernie Sanders, have refused to attend private fundraisers with wealthy donors and have said Buttigieg's style of fundraising breeds corruption.

Buttigieg, who leads the Democratic field in recent polls of Iowa and New Hampshire, hit back against these charges in a tense portion of Thursday night's debate.

He said it would be self-defeating to turn away donations while engaged in "the fight of our lives" against President Trump, and he pointed out how Warren, in her senatorial career, had accepted money from similar donors.

His argument: Private fundraisers didn't corrupt her, and they aren't corrupting him.

Buttigieg has insisted that raising money from wealthy donors does not and could not corrupt his campaign.

But the donor who received the Buttigieg fundraiser's email felt differently. "He's running on an image that may not be his reality."

The backstory: H.K. Park works for the global business consultancy The Cohen Group, headquartered in Washington, D.C.

Campaigns refer to people like Park as "bundlers." They bundle together donations from rich friends and colleagues and are among the highest value assets to traditional campaigns. Sanders and Warren have pledged not to raise money this way.

The Cohen Group's chairman and CEO is William Cohen, a former U.S. senator and secretary of defense. Trump's former Secretary of Defense Jim Mattis is a senior counselor for the group.

Under criticism for holding closed-door fundraising events, Buttigieg recently agreed to disclose the names of his campaign's fundraisers and to open events to the media.

However, an internal campaign fundraising report obtained by Politico revealed that Buttigieg's campaign omitted more than 20 major fundraisers from its list, including the names of "uberwealthy supporters" such as Boston power broker Jack Connors Jr. and hedge fund investor John Petry.

report obtained by Politico revealed that Buttigieg's campaign omitted more than 20 major fundraisers from its list, including the names of "uberwealthy supporters" such as Boston power broker Jack Connors Jr. and hedge fund investor John Petry. The Buttigieg campaign told Politico that the error took place when updating their list of bundlers: "In creating this updated list, we went through to recalculate totals from the earlier list to make sure we were being accurate," Buttigieg's spokesperson Chris Meagher said in a statement to Politico.

that the error took place when updating their list of bundlers: "In creating this updated list, we went through to recalculate totals from the earlier list to make sure we were being accurate," Buttigieg's spokesperson Chris Meagher said in a statement to Politico. During that process, some names that were previously included on a list to donors were "inadvertently" withheld from the disclosure to the public.

By the numbers: Buttigieg's campaign has raised more than $50 million, according to data released by the Federal Election Commission on Dec. 16.

Roughly $27 million of that (or 52%), was raised through large-dollar contributions, per OpenSecrets. By comparison, Sanders and Warren raised around 25% and 30% of their totals, respectively, from large-dollar contributions — defined as anything over $200.

Buttigieg is especially popular in Silicon Valley, with employees of Google, Facebook, Apple and Amazon among his biggest contributors, per OpenSecrets.

Facebook CEO Mark Zuckerberg says he's advised Buttigieg on staff hires but has stopped short of an endorsement.

Silicon Valley's richest families are also raising money for Buttigieg, per Recode, including Netflix CEO Reed Hastings, the wife of Google co-founder Sergey Brin, the wife of former Google CEO Eric Schmidt, and the sister of Facebook COO Sheryl Sandberg.

Go deeper: "Billionaires in wine caves": Buttigieg and Warren clash over big-dollar donations