A top adviser on Sen. Bernie Sanders Bernie SandersThe Hill's Campaign Report: Trump faces backlash after not committing to peaceful transition of power Bernie Sanders: 'This is an election between Donald Trump and democracy' The Hill's 12:30 Report: Trump stokes fears over November election outcome MORE’s (I-Vt.) presidential campaign argued Thursday that the 2020 White House hopeful is an “existential threat” to moderate Democrats who have ties to Wall Street.

“Bernie Sanders is an existential threat to that faction of the Democratic Party,” David Sirota, a speechwriter and senior adviser to Sanders, told Hill.TV while referring to Democrats who receive donations from Wall Street firms.

“Bernie Sanders is an existential threat to Wall Street continuing to rip off Americans as a business model — a business model of fraud,” he added.

Sirota was responding to criticism from center-left think tank Third Way. Last month, the group’s president Jon Cowan called Sanders an “existential threat to the future of the Democratic Party for the next generation,” according to a report by The Guardian.

“He has made it his mission to either get the nomination or to remake the party in his image as a democratic socialist,” Cowan told The Guardian in South Carolina. “That is an existential threat to the future of the Democratic party for the next generation.”

Sanders later hit back on Twitter, embracing the label.

“The Wall Street-funded @ThirdWayTweet thinks we are an existential threat — and they're right. We are an existential threat to the corporatism and greed that keeps their donors in power,” he tweeted.

Sirota echoed Sanders's remarks Thursday, calling Sanders "an existential threat" to the organization itself, which he dubbed "a Wall Street group."

The exchange between the campaign and Third Way came after Sanders gave a speech last month defending democratic socialism, a term the independent Vermont senator has long used to describe his policy views.

During the speech at George Washington University, the Democratic presidential hopeful posed the political philosophy as the ultimate counter to President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE’s nationalism.

“While President Trump and his fellow oligarchs attack us for our support of democratic socialism, they don’t really oppose all forms of socialism,” he said. “They may hate democratic socialism because it benefits working people, but they absolutely love corporate socialism that enriches Trump and other billionaires.”

—Tess Bonn