Robert M. Cornicelli, a veteran and advocate for veterans and the developmentally disabled who is seeking the Republican Party’s nomination to represent New York’s First Congressional district, has announced that retired Lt. Gen. Michael T. Flynn, a former national security adviser to President Trump, has endorsed his candidacy.

As a car and truck caravan of supporters of former President Donald Trump packed Main Street in Montauk, having rolled across eastern Long Island with horns blaring and flags waving, a small explosive was thrown from a white pickup truck, apparently by one of the participants.