WASHINGTON » After months of trading vicious insults, Donald Trump and Marco Rubio are suddenly making nice.

Trump has added his voice to the growing chorus of Republicans encouraging Rubio to run for re-election to the Senate, despite mocking him for months as “Little Marco” and insisting he “couldn’t get elected dogcatcher” in Florida.

And Rubio is returning the favor, going on CNN to declare he’d be “honored” to speak at the Republican National Convention in favor of Trump, the same person he trashed as a “a con man who’s pulling the ultimate con job on the American people.”

As always in politics, the new alliance is about expediency. Trump has apparently decided he needs Rubio to help keep the Senate in GOP hands, a stance being promoted by Senate Republicans from Majority Leader Mitch McConnell on down this week. And Rubio, who is seen as having ambitions to run again for president in 2020, can’t easily afford to alienate Trump and his many supporters.

“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 wrote on Twitter Friday in defense of his newfound embrace of the presumptive GOP nominee, though he still stopped short of endorsing Trump.

And Trump went on Twitter to encourage Rubio to run for re-election, noting that polling shows he’s the most likely to keep the seat in GOP hands and arguing it’s important for Republicans to hang onto their Senate majority. “Run Marco!” Trump wrote.

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.

Indeed, on Friday Rubio joined a fundraising call with donors in Florida in support of Lopez-Cantera, according to two Republicans familiar with the call. It was a pep talk to donors to finish the quarter strong and defused talk that Rubio would get in the race. Instead he encouraged donors to back Lopez-Cantera, according to the Republicans, who spoke on condition of anonymity to discuss the private call.

But Rubio acknowledged publicly he’s under pressure to change his mind.

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.

A McConnell-aligned super PAC dedicated to helping Senate Republicans announced plans Friday to get involved in Florida, but only if Rubio runs.

“Florida is a huge financial commitment. We felt confident about betting on Rubio back in 2010 and would do it again in a heartbeat, but right now it’s hard to imagine making that same investment without him as our candidate,” said Steven Law, a former McConnell chief of staff and head of the Senate Leadership Fund.

On the Democratic side the establishment is behind Rep. Patrick Murphy who faces flamboyant progressive Rep. Alan Grayson in the primary.