https://blog.thebeardclub.com/2018/11/06/where-are-the-beards-in-politics/
Although there is very limited research into the dynamic between politician’s facial hair and voting, there’s been a couple of good guesses. Currently, facial hair is rare among modern politicians. It’s estimated that fewer than five percent of the members of Congress have either beards or mustaches.
Many political analysts have learned that many voters base their choices off of trivial or superficial traits they see in their candidate of choice. Lately, assessments of appearance haven’t fared well for our bearded representatives.
https://www.businessinsider.com/why-male-politicians-dont-have-facial-hair-2015-6
"Using an experimental method, Herrick and her colleagues showed people photographs of similarly appearing politicians with and without facial hair, asking them how they felt about the men and their likely positions.
They found that potential voters perceived men with facial hair to be more masculine and this was a double edged sword. Higher ratings of masculinity were correlated with perceptions of competence, but also concerns that the politicians were less friendly to women and their concerns.
In other words, the more facial hair, the more people worry that a politician might be sexist.
In reality, facial hair has no relationship to a male politician’s voting record. They checked. The research suggests, though, that men in politics — maybe even all men — would be smart to pay attention to the stereotypes if they want to influence how others see them."
https://scholars.org/contribution/why-beards-and-mustaches-are-rare-modern-american-politicians
Today, research and theory suggest that voters may stereotype men with facial hair. Perceptions of men with facial hair as especially competent, composed, aggressive, powerful, or bold can obviously have upsides for candidates. But there are also downsides, because voters may stereotype politicians with facial hair as likely to hold issue positions inimical to feminists, such as opposition to reproductive choice for women. Voters may also see men with beards and mustaches as more supportive of gun rights, military spending, and the deployment of force.