Women are at least 50% (give or take) of the electorate.
However, they clearly are a small fraction of elected politicians.
There are plenty of reasons why a woman may not want to run for office in the first place (your prefered reason may vary with your ideology).
However, what is puzzling, is why do women (or any other identity-politics aficionados who care more about gender than a person's individual qualities) who complain about lack of women being elected, don't actually put their money where their mouths are and support and vote for those women who DO run for office?
This isn't even a partisan thing - plenty of women vote for a man in Democratic primaries featuring both genders, where the standard idiotic explanation of "female candidate is a Republican woman and thus anti-women as all Republicans are" doesn't fly. Let's take the most high-profile case: 2008 Clinton/Obama primaries:
- Young women supported Obama by 53-45 percent on Super Tuesday (src)
- Same Super Tuesday, general gender gap was mostly ~10% (src); with NO STATE aside from Clinton's home Arkansas having >60% of women vote for her and many states <50% voted for her
- Another stats for the whole nomination in 2008: Hillary Clinton got only 51.5% total female votes vs. Obama's 48.5% (src)