Vermont Sen. Bernie SandersBernard (Bernie) SandersTrump has declared war on our climate — we won’t let him win Stock slide bites boastful Trump, but rising wages great for GOP Millions should march on DC to defeat Trump Republicans MORE may have provided Hillary ClintonHillary Diane Rodham ClintonTrump touts report Warner attempted to talk to dossier author Poll: Nearly half of Iowans wouldn’t vote for Trump in 2020 Rubio on Warner contact with Russian lobbyist: It’s ‘had zero impact on our work’ MORE with campaign advertisement fodder at Monday night’s Democratic presidential forum in Iowa, acknowledging that his healthcare plan will require raising taxes.

Sanders was pressed on the specifics of his Medicare For All healthcare plan, which he has said will require a tax hike but which he claims will save individuals money overall by eliminating private healthcare premiums.

“We will raise taxes, yes we will,” Sanders declared, calling criticim of his plan “disingenuous.”

But Clinton allies were already taking to Twitter to hammer Sanders for the remarks.

The Clinton campaign has accused Sanders of seeking to dismantle ObamaCare to implement a single-payer system, warning that he risks giving away gains liberals have made under the Affordable Care Act.

Some have questioned that line of attack; the single-payer system is popular among liberal primary voters.