One Knight Only by Peter David
Star Trek fans may recognize Peter David as the author of such books as Q-in-Law, Q-Squared, and Imzadi, but he has also written some interesting fantasy. In Knight Life, King Arthur is released from his imprisonment and, at Merlin’s behest, runs for mayor of New York City. In the sequel, One Knight Only, Arthur is now president of the United States, having successfully run as an independent. He enjoys high approval ratings and has focused his attention on fighting terrorism. However, after his wife Gwen is shot by a terrorist and slips into a coma, Arthur resigns the presidency, sends a basilisk after the terrorist group responsible, and sets off on a quest for the Holy Grail.
I wouldn’t put this book as Peter David’s best work, but it was interesting enough to read straight through a few days ago. If you liked the books I mentioned above, then One Knight Only is worth a look.