The Gentleman from California — Niven Busch

In politics, the rise to the top can also correspond to the erosion of one's moral core. Ask Aline Cleary Belshaw ― her father was an honest and popular senator and she grew up immersed in the excitement of political life, believing in the unshakable fiber of the political process. So when she marries a grass-roots lawyer with political ambitions, she is happy to support him in every way. Until, of course, she discovers that his integrity is disappearing along with every toehold.
Clay Belshaw thinks he is doing what he needs to do in order to make his way in the “the hair pulling and groin kicking of everyday politics.” Although his wife is shaken by the devious compromises he is willing to make, Clay's career continues to flourish and he unexpectedly creates the candidate everyone is looking for. “It was easy―almost inevitable―to center your dreams and hopes on such a man, to believe, no matter what some said to the contrary, that he would make life better and simpler for you, that he could and would restore to the nation some old-time good that, due to the corruption of others, had gone out of it.”
Sound familiar? Even if political conniving and scheming is old hat by now, published in 1965, The Gentleman from California will interest readers seeking a fictionalized account of U.S. politics, pre- and post- WW II, and the impact of ambition on the lives of those who rise to power.