evidence: More than a century later, that question remains stubbornly unanswered. Nikki Haley’s suspension Wednesday of her campaign for the GOP presidential nomination makes her the latest in a long line of women with presidential hopes to crash against the monolith of a man — in this case, Republican Donald Trump — in a nation founded on the concepts of equality and opportunity for all. [...] Polls show most Americans do not necessarily oppose electing a woman president, hypothetically. And this year, Haley notched some history: She’s the first woman to win a Republican presidential primary, in the District of Columbia; she also won in Vermont. Supporters and analysts say she may have developed a playbook for confronting the former president who dominates the Republican Party — and for running in the post-Trump era. [...] Haley’s exit from the presidential contest sets up a rematch few people want between two white men of advanced age — Democratic President Joe Biden, 81, and his predecessor, Republican Donald Trump, 77.