Former Hewlett-Packard CEO Carly Fiorina announced her candidacy for president Monday, joining an ever-more-crowded field of Republican competitors. She tweeted “I am running for president” Monday morning, with a link to her new campaign website, before formally launching her campaign on ABC's Good Morning America. Retired neurosurgeon Ben Carson also said Sunday he is running for president in an interview with CBS News Cincinnati affiliate WKRC, and formally launched in Detroit on Monday. “I’m willing to be part of the equation, and therefore I’m announcing my candidacy for president of the United States of America,” he said. Republican Sens. Ted Cruz of Texas, Rand Paul of Kentucky, and Marco Rubio of Florida have declared their candidacies for the Republican ticket.