President Barack Obama on Thursday criticized Donald Trump for making a “dangerous” threat to reject the outcome of the presidential election, but saved some of his sharpest criticism for Florida Republican Sen. Marco Rubio.

Obama delivered much of his now-familiar stump speech at a college in Miami, touting what he sees as his administration’s major economic and other achievements. As he has for several weeks, the outgoing president talked up Democratic presidential nominee Hillary Clinton and threw sharp elbows at Trump, her GOP opponent.

Hours after Trump doubled down on his resistance at the final presidential debate Wednesday night to say he would accept the election results only if he won, Obama labeled his antics “dangerous.”

“This is more than just the usual standard lie,” Obama said. “Because when you suggest rigging or fraud without a shred of evidence, … when he becomes the first major party nominee in modern history that says he will not concede, … that is not a joking matter. That is dangerous.”

Obama warned that Trump’s threat “undermines democracy” and would do “the work of our adversaries for them.”

[Obama Tells Trump to ’Stop Whining,’ Campaign Harder]

Earlier Thursday, at a rally in swing state Ohio, the GOP nominee made a spectacle of his pledge, telling a rally that he “would like to promise and pledge to all of my voters and supporters and to all of the people of the United States that I will totally accept the results of this great and historic presidential election — if I win.”

That followed this from the debate when he was asked if he would call Clinton to concede on election night should he fall short: “I will look at it at the time. … I will keep you in suspense.”

Obama described Trump’s message as a “dark, pessimistic, fear-mongering vision of a country.” He also jabbed at the reality television star-turned-politician for allegedly not paying income taxes for nearly two decades, saying Trump is “not part of the solution, he’s part of the problem.”

But much of Obama’s speech, and most of his hardest punches, came at Rubio’s expense. The president cast Rubio’s opponent, Democratic Rep. Patrick Murphy, as putting Floridians’ best interests ahead of his own career ambitions — unlike Rubio.

“Unlike his opponent, he actually shows up to work,” Obama said of Murphy.

Obama questioned how Rubio could months ago call Trump a “dangerous con artist,” but still intend to vote for him as Election Day approaches. He also accused the Florida senator of being willing to “say anything” to win the Senate race.

“Marco just seems to care about hanging onto his job,” Obama said. “Patrick Murphy cares about you.”

[Trump on Assault Accusations: ‘Pure Fiction and Outright Lies’]

The Rothenberg & Gonzales Political Report/Roll Call has the race as leaning Republican. The latest RealClearPolitics average of recent polls gives the GOP incumbent a nearly 5-point lead.

In an attack line that could resonate in heavily Hispanic South Florida, the president hit Rubio for abandoning an immigration overhaul bill he helped write, saying Murphy “didn’t walk away from Florida’s Hispanic community when things got tough.”

Rubio’s congressional GOP colleagues were also targeted, with Obama questioning how they could support Trump’s rhetorical cozying up to Russian President Vladimir Putin, after criticizing Obama for just “talking to” Moscow’s strongman.

Slipping into his folksy persona, Obama asked rhetorically of GOP lawmakers: “Now suddenly you’re OK with your nominee having a bromance with Putin?”

Contact Bennett at johnbennett@cqrollcall.com. Follow him on Twitter @BennettJohnT.