Young African-American voters are picking Bernie Sanders over Hillary Clinton in the Democratic primary race, revealing a generational rift in which millennials are eschewing a penchant among their elders for the Clintons dating back to the 1990s, when Bill Clinton ran away with the black vote.

They are showing up in too few numbers to give the Vermont senator much of a boost. Nevertheless, that many millennials prefer Sanders’ progressive agenda shows there are cracks in Clinton’s domination of the African-American electorate.