Two men in their late seventies, with over 70 years combined experience in Washington, have sat among the top three in the Democratic field for months, taking shots at other candidates—but largely avoiding the other.

That changed in the hours following the Democratic debate in Ohio during which former Vice President Joe Biden took aim at Medicare for All —s pecifically Sen. Elizabeth Warren’s (D-MA) plan — as expensive and unrealistic.

By the next day, Biden had turned his fire on Sen. Bernie Sanders (I-VT).