The Biden-Sanders rivalry embodies a key debate happening within the Democratic Party: Should Democrats nominate a bold progressive who pushes the debate further left, or should they elevate a more moderate centrist who could potentially appeal to independents and disaffected Republicans?

Sanders, an independent senator who identifies as a Democratic socialist, is the furthest left of all the potential candidates. Forty-four percent of likely Democratic caucusgoers say he’s “too liberal” — more than for any other candidate tested. Forty-eight percent say his political views are “just right,” 2 percent say he’s “too conservative” and 7 percent are unsure.

According to the poll, he appeals most to those who do not identify with any particular religion (37 percent) and those younger than age 35 (34 percent).

But, generally, likely Democratic caucusgoers say they are OK with candidates who think the country should be more socialist.