Elizabeth Warren is dropping out of Democratic race for president, so who will get her votes? It’s complicated.

In what turned out to be the final rally of her presidential campaign, Elizabeth Warren had some advice for more than 2,000 voters jammed into a giant shed at Detroit’s famed Eastern Market.

Instead of tracking the horse race talk and pundit predictions, Warren said they should, “cast a vote that will make you proud, cast a vote from the heart.”

Her plea may still apply, but another candidate will become the beneficiary after news surfaced Thursday that Warren is ending her campaign following a series of stinging defeats on...