In a new Pew poll, 41% of Dems say it bothers them that their nominee will be a white male in his 70s and 59% say it doesn't. By race:

White
Bothers 49%
Doesn't bother 51%

Black
Bothers 28%
Doesn't bother 72%

Hispanic
Bothers 30%
Doesn't bother 70% https://www.pewresearch.org/fact-tank/2020/04/20/some-democrats-are-bothered-nominee-is-an-older-white-man-and-they-solidly-back-biden-in-november/

Supporters of Dem candidates bothered that nominee will be white male in his 70s:

Biden supporters
Bothers 21%
Doesn't bother 79%

Sanders
Bothers 42%
Doesn't bother 58%

Buttigieg
Bothers 57%
Doesn't bother 43%

Warren
Bothers 73%
Doesn't bother 26%