Sen. Bernie Sanders (I-Vt.) tops the list of former Vice President Joe Biden’s potential running mates, according to a Harvard CAPS/Harris Poll survey released exclusively to The Hill. The poll shows that 1 in 5 registered voters — 20 percent — prefer Sanders for Biden’s vice presidential slot, the highest support of any would-be running mate presented to respondents in the survey. But Sanders is unlikely to be considered, if not entirely ruled out, as Biden’s running mate in the general election. Biden vowed last month to choose a woman as his vice presidential pick and has said he’s considering a list of between six and 10 candidates for the job.