Hours before the first major elections since  Donald Trump’s win last November, Sen. Bernie Sanders offered a stern warning for Democrats about the party’s closed-door talks to end the shutdown.

Inside a tense, three-hour meeting at the Capitol on Tuesday, a fiery Sanders urged Democrats not to yield to Republicans without a real victory on health care. The Vermont independent was armed with fresh polling from a Democratic-aligned firm that showed voters would punish the party for giving up with nothing in return, according to a person familiar with his remarks.

By Wednesday morning, Sanders and his colleagues in Congress pointed to Democrats’ blow-out victories — including in Virginia, a state with thousands of furloughed federal workers — as the most powerful evidence yet they needed to keep fighting.