(today)

Former Gov. Deval Patrick of Massachusetts officially entered the presidential race on Thursday, adding an 18th candidate and an 11th-hour twist to a turbulent Democratic primary with less than three months to go before the Iowa caucuses.

Mr. Patrick’s announcement, which he had signaled this week, came in the form of a video he released early Thursday morning. In it, he said he was running for people who “feel left out” and want a future “not built by somebody better than you, not built for you, but built with you.”