Trump derided Rubio as "Little Marco" on the presidential campaign trail and remarked in March that "the people of Florida can't stand him. He couldn't get elected dogcatcher."
But now Trump says over Twitter that polling shows Rubio has the best chance of keeping his Senate seat in GOP hands, and that it's important for Republicans to keep their majority.
"Run Marco!" Trump writes. Rubio told reporters this week he's "unlikely" to reconsider his plans to retire from the Senate, especially since a good friend of his, Lt. Gov. Carlos Lopez-Cantera, is in the race.
But he acknowledged he's under pressure, with Senate leaders including Majority Leader Mitch McConnell weighing in to get him to run. The primary in Florida is in late August and the filing deadline is June 24.
A half-dozen Republicans are already running but none is well-known and statewide campaigns in Florida cost millions. Republicans are defending 24 Senate seats nationwide as they struggle to hang onto their slim Senate majority and fear a loss in Florida.
On the Democratic side the establishment is behind Rep. Patrick Murphy who faces flamboyant progressive Rep. Alan Grayson in the primary.
Rubio, who denounced Trump as a "con man" during the presidential race, also is moving to mend fences though still without endorsing the presumptive GOP nominee. "If you can live with a Clinton presidency for 4 years that's your right. I can't and will do what I can to prevent it," Rubio said over Twitter today.