A top official for 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.) campaign fired back at 2020 presidential rival Joe Biden Joe BidenPelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Hillicon Valley: Subpoenas for Facebook, Google and Twitter on the cards | Wray rebuffs mail-in voting conspiracies | Reps. raise mass surveillance concerns Fox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio MORE on Wednesday after he criticized Sanders's health care plan.

Nina Turner, co-chairwoman of Sanders’s campaign, accused the former vice president of lying about about the senator's proposed government-run “Medicare for All” plan during an AARP presidential forum in Iowa on Monday.

“Matter-of-fact, he gave a speech to the AARP — just flat out lied — trying to scare elderly folks, and I really did not think that the vice president would go to that length,” Turner told Hill.TV during an interview on "Rising."

"It's one thing to want to win the nomination, it's another thing to do anything to win it," she continued.

The Biden campaign did not immediately respond to Hill.TV's request for comment.

Turner pushed back on Biden's comments from the AARP forum in which he emphasized that under his own proposal those who have employer-based insurance can keep it.

Biden, who is running on protecting ObamaCare, contrasted his plan to give Americans a Medicare-like public option with the Medicare for All plan being championed by Sanders and other liberals that would reject private insurance for government-run health care.

The former vice president maintained that under his plan people wouldn’t be forced to give up their health care coverage if they prefer to stay on their own plan.

“If you like your health care plan, your employer-based plan, you can keep it. If in fact you have private insurance, you can keep it,” Biden said.

Turner went after those comments Wednesday, arguing that all Americans — particularly elderly people — will have a choice to expand their coverage under a Medicare for all system, though such a plan would reject private insurance.

“They will have vision, they will get hearing aids, they will have dental — things that they do not have now, so there are times you can just go too far to prove a point — and lying is one of them,” she said.

Turner’s comments mark the latest clash between the Biden and Sanders campaigns as Sanders seeks to claw into Biden's lead in the Democratic primary.

In an interview with The Washington Post on Tuesday, Sanders called Biden’s critique of his “Medicare for All” plan “absurd.” He also took aim at Biden’s prosed health care plan.

“Times change, and we have got to go further,” Sanders said, before adding “of course he’s wrong.”

Even though Biden’s favorability has slipped below 30 percent in recent months, he remains the front-runner in the crowded Democratic primary field.

Sanders is set to deliver a speech on his Medicare for All proposal Wednesday. In an online preview of his speech, Sanders argued that the debate over health care is all about political power.

“When we fight for Medicare for All, we’re not just taking on the Republican Party and Donald 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, we’re not just taking on elements of the Democratic Party — we’re taking on one of the most powerful industries in the world,” he said. “An industry — the health care industry — that has unlimited resources and they will use those resources to protect their profits.”

—Tess Bonn