ASSOCIATED PRESS/Eric Gay, File Rep. Beto O'Rourke (D-Texas), the 2018 Democratic nominee for U.S. Senate in Texas, makes his concession speech at his election night party in El Paso, Texas.

The progressive commentariat has been buzzing in recent weeks about the barrage of unflattering reporting and criticism directed at retiring Texas Rep. Beto O’Rourke (D) by left-leaning journalists and activists.

Although Vermont Sen. Bernie Sanders’ team insists he has had nothing to do with the criticism and there is no evidence to suggest he has, many of his supporters have indeed been peeved by the boomlet of hype around O’Rourke following his 3-percentage-point loss in the race for a Senate seat in Texas.

But there is a specific factor driving the frustration of some diehard “Berniecrats” that has thus far received little attention: The defection of key alumni from Sanders’ 2016 presidential run to the O’Rourke camp and the resulting worry that they will provide a progressive coat of paint for the Texan’s more moderate record.

Becky Bond and Zack Malitz are two of those figures. The pair had a major role in shaping Sanders’ innovative “distributed” organizing model that the candidate used to empower decentralized, self-organizing groups of volunteers in lieu of a much larger, more expensive cohort of field staff. They masterminded a similar setup for O’Rourke in his 2018 Senate run.

Bond and Malitz have already pledged themselves to O’Rourke if he jumps into the presidential race.

“They are using their Bernie credibility to whitewash Beto’s policies,” said a progressive strategist sympathetic to Sanders who declined to be named for professional reasons. “It’s Bernie-washing.”

As for those policies, progressive critics point to a number of examples. O’Rourke, a member of the business-friendly New Democrat Coalition, has voted for bills lifting the ban on exporting crude oil and granting presidents a fast-track approval process for international trade agreements. Over three terms in Congress he also failed to sign on to a single-payer health care bill that had the support of the majority of House Democrats, though as a Senate candidate he said that if elected, he would support Sanders’ Medicare for All bill.

Bond and Malitz aren’t the only Sanders alumni likely to bolt for O’Rourke’s team if he runs.

O’Rourke also tapped Middle Seat, a digital strategy and fundraising firm founded by Sanders alumni Kenneth Pennington, Hector Sigala and Elizabeth Bennett, to run the digital operation for his Senate campaign. And Linh Nguyen, another former Sanders digital staffer, migrated to O’Rourke’s Senate campaign as well.

The New York Times reported that Middle Seat is “hoping” to join a potential O’Rourke 2020 bid as well; Pennington declined to comment in response to a HuffPost inquiry.

Sanders’ most ardent supporters say they are not worried that O’Rourke will deprive Sanders of top organizing firepower or signal an exodus of former Sanders talent to the O’Rourke team in the event that both men run for president.

Tim Tagaris and Robin Curran, who led Sanders’ digital fundraising team, have already pledged to return to the Sanders fold, according to the Sanders campaign. And Pennington had a public falling out with Jeff Weaver, Sanders’ longtime adviser and 2016 campaign manager, in August 2016, long before O’Rourke became a nationally recognized figure.

Sanders’ midterm campaign swing showed there “is a tremendous outpouring of support [for him] that still exists at the grassroots level,” Weaver told HuffPost. “I have an email inbox and voicemail full of messages from former staffers who want to rejoin a campaign if it happens.”

Weaver would not comment on O’Rourke or any other potential candidates.

But some Sanders loyalists nonetheless fear that the presence of some high-profile Sanders alumni closely associated with Sanders’ most successful tactics will obscure O’Rourke’s centrist policy record.

“People are saying O’Rourke is a bridge to the Bernie wing because of Zack and Becky,” the progressive strategist said.

Even if Bond, Malitz and other Sanders alumni have not magnified O’Rourke’s notoriety by association, they certainly have done so by leveraging the Sanders playbook to help O’Rourke succeed, according to Charles Lenchner, a co-founder of The People for Bernie Sanders, a pro-Sanders group with a big social media following that is not tied to the campaign.

The use of campaign tactics and the enthusiasm they generate among the grassroots is effectively used as a substitute for policy. Charles Lenchner, the People for Bernie Sanders

Now Lenchner and others worry that establishment Democrats like Center for American Progress President Neera Tanden and former Obama adviser David Axelrod are excited about O’Rourke precisely because he provides an opportunity to tap into the youth vote that Sanders excited without Sanders’ left-wing policies. These Sanders acolytes see a precedent for it in the way that former President Barack Obama’s dynamic organizing style obscured a more centrist governing record.

“The use of campaign tactics and the enthusiasm they generate among the grassroots is effectively used as a substitute for policy,” said Lenchner, who is now digital director of the left-wing news outlet The Real News.

Murshed Zaheed, who worked with Bond and Malitz at the progressive cellphone company Credo Action and emphasized his deep admiration for Bond, nonetheless shared Lenchner’s concern.

O’Rourke “wants to take the tactical underpinnings of the Bernie campaign and put his polish on it, but not necessarily in a way that is progressive on policy,” said Zaheed, who is now a principal at the left-leaning consulting shop Strategy and Hustle, and has not yet settled on a candidate in the 2020 presidential election. “Grassroots organizing does not make a candidate progressive.”

“I know that Becky [Bond] and Zack [Malitz] found Barack Obama’s presidency to be disappointing. So it doesn’t add up then,” said Anthony Rogers-Wright, an African-American climate justice activist and former member of Sanders’ policy team.

Referring to Rules for Revolutionaries, Bond’s 2016 book with fellow Sanders alum Zack Exley, Rodgers-Wright quipped, “That’s not Beto. I could see that book being more applicable to [former Florida gubernatorial candidate] Andrew Gillum than Beto O’Rourke.”

In fact, in some ways, O’Rourke’s record is more conservative than Obama’s. As journalist David Sirota, who briefly worked for Sanders in the early 2000s, noted in his exhaustive analysis of O’Rourke’s legislative history, the El Paso congressman voted for bills undermining the Consumer Financial Protection Bureau, the creation of which Obama oversaw.

Still, Bond, Malitz and the other Sanders alumni drifting toward O’Rourke have their defenders within Bernie World. Shaun King, a black civil rights activist who was a top surrogate for Sanders in 2016, joined Bond in co-founding the Real Justice PAC, a group dedicated to electing more progressive prosecutors, in February. He said his friendship with Bond and Malitz contributes to his confidence in O’Rourke.

“They grew to believe in Beto like I think they grew to believe in Bernie. It’s real,” King said.

“They would have no interest in putting progressive clothes on Beto,” he added. “They believe he is a deeply progressive person and will be a deeply progressive leader.”

ASSOCIATED PRESS/J. Scott Applewhite Sen. Bernie Sanders (I-Vt.), joined at left by Sen. Chris Murphy (D-Conn.), holds a news conference after the Senate passed a resolution pulling aid from the Saudi-led war in Yemen.

Asked to respond to some of the criticism herself, Bond sent HuffPost the unabridged text of a statement she previously provided to The New York Times explaining her support for a would-be O’Rourke presidential run. In it, Bond emphasized O’Rourke’s freewheeling campaign style and commitment to reaching voters in person.

“There’s no other 2020 contender who has had the sheer number of conversations with voters as Beto has over the past two years,” she said.

She also stressed O’Rourke’s strengths as an advocate for immigration reform and racial justice. (The most viral moments of O’Rourke’s Senate campaign featured him eloquently denouncing police killings of unarmed black men and the right of football players like Colin Kaepernick to protest those killings.)

“What other potential candidate has addressed the refugee and immigration crisis as boldly or compellingly as Beto has?” she wrote. “And this country needs a leader with the moral clarity on racial justice that Beto demonstrated again and again on the campaign trail in Texas.”

But it’s precisely because turning out voters of color, and championing issues that affect them directly, is such a high priority for any Democratic candidate that some Democrats outside of Sanders’ camp question whether O’Rourke, a white man, is really the right choice in a field that is likely to include several nonwhite contenders.

Steve Phillips, a prominent Democratic donor who started a super PAC in support of a likely presidential run by New Jersey Sen. Cory Booker, believes Booker is best poised to “rebuild the Obama coalition” of voters of color and white progressives.

Phillips has encouraged O’Rourke, Gillum and former Georgia gubernatorial candidate Stacey Abrams ― all of whom lost by narrow margins ― to run again for statewide office rather than jumping in the presidential pool.

Still, he wonders why O’Rourke’s impressive but ultimately failed Senate bid has generated more presidential buzz than the gubernatorial runs of Gillum and Abrams, both of whom are black and lost by fewer percentage points than O’Rourke did.

“These things get to questions about implicit bias about who people see as leaders and who people don’t see as leaders,” Phillips said. “There is some level of risk and concern that the stampede to Beto is replicating some of the less savory aspects of implicit bias.”