Trump ramps up feud with San Juan mayor ahead of Dorian

With a hurricane watch now in effect for Puerto Rico, President Donald Trump on Wednesday insulted San Juan Mayor Carmen Yulin Cruz, before proclaiming himself “the best thing that’s ever happened to Puerto Rico.”

The president initially tweeted a prediction that the Federal Emergency Management Agency, or FEMA, and others will do "a great job" responding to Tropical Storm Dorian in Puerto Rico and “When they do, let them know it, and give them a big Thank You - Not like last time.”

With Trump calling Yulin Cruz, a Democrat, “incompetent,” and the mayor on Tuesday urging Trump to “get out of the way,” the adversaries have reignited a feud dating back to the wake of Hurricane Maria.

In a second Twitter thread later Wednesday morning, Trump proclaimed himself “the best thing that’s ever happened to Puerto Rico!”

FEMA announced late Wednesday morning that the president signed an emergency declaration for Puerto Rico, making federal emergency aid available there to supplement the local response and authorizing FEMA "to identify, mobilize, and provide at its discretion, equipment and resources necessary to alleviate the impacts of the emergency."

On Tuesday, Trump made the false claim that Congress had approved $92 billion for the U.S. territory after Hurricane Maria devastated the island in 2017.

Congress has allocated only about $42 billion -- and only a smaller portion of that has been spent. But Trump and the White House have repeatedly used the $92 billion figure -- based, they say, on a government estimate of how much recovery money the island could need over 20 years.

ABC News' Elizabeth Thomas contributed to this report