Article snippet: On the GOP side, President Trump faces a real possibility of a primary challenge from one or more Republicans. And on top of all that, there are some independents who are considering mounting a third-party bid for the nation’s highest office. We’re keeping track of where all possible presidential candidates stand: Who’s running, who isn’t running, and, when the time comes, who has dropped out. We’ll be updating this list as candidates declare their intentions, so keep checking in. © 2019 Boston Globe Media Partners, LLC Link to the full article to read more