Death Before Bedtime — Edgar Box

In Death Before Bedtime, dashing P.R. man Peter Sargent is invited to the home of a venerable senator to help strategize his imminent run for president.  On the night before he's to announce, though, the senator is murdered in his bed.  No longer needed as a political publicist, Sargent finds himself helping the police find the killer.  He deftly navigates an eccentric cast of characters, all of whom are suspects: the rebellious daughter; the sycophantic aide; the grieving widow; and the power-hungry governor with his eye on the senator's job.  Somehow, between charming the senator's daughter and glad-handing Washington's elite, Sargent still manages to methodically put the pieces into place and sees that politics truly is a cut-throat business.