WESTERVILLE, Ohio — The question was inevitable. Elizabeth Warren’s answer was the same. And her rivals seized on it.

For the second consecutive debate, Warren refused to say whether middle-class Americans would pay higher taxes under her proposed “Medicare for All” plan. It was a glaring dodge for a candidate who has risen to the top of the Democratic field by unveiling detailed policy proposals and selling them with a folksy flair.

And it was one of nearly half a dozen issues on which Warren found herself defending the broad ambition she has laid out to remake the American economy and rebalance the nation’s wealth. More moderate candidates, including Joe Biden, Pete Buttigieg and Amy Klobuchar, cast Warren as unrealistic and vague.

How Warren handles that criticism, which was abundant Tuesday and is likely to escalate in the coming weeks, will be a central test of whether she can maintain her standing.