LANSING, Mich. — Michigan Republicans on Saturday picked Kristina Karamo to lead the party in the battleground state, fully embracing an election-denying Trump acolyte after her failed bid for statewide office, one in which she unsuccessfully sued to throw out mail-in votes in Detroit and refused to concede. Ms. Karamo won a majority of delegate votes at the state party’s convention in Lansing, the state capital, after three rounds of voting that — slowed by paper ballots and hand counting — went on hours longer than the period for which the party had originally rented the convention space. Her victory...