Vermont Sen. Bernie SandersBernard (Bernie) SandersWorld leaders reach agreement on trade deal without United States: report Sanders on Brazile revelations: DNC needs ‘far more transparency’ Sen. Warren sold out the DNC MORE may have provided Hillary ClintonHillary Diane Rodham ClintonGOP rushes to cut ties to Moore Papadopoulos was in regular contact with Stephen Miller, helped edit Trump speech: report Bannon jokes Clinton got her ‘ass kicked’ in 2016 election 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.