RICHMOND, Va. -- Donald Trump, the presumptive Republican presidential nominee, issued a new warning to President Obama on Friday as he went after old enemies like Hillary Clinton and Elizabeth Warren at his first campaign rally since the end of the Republican and Democratic primary contests in Richmond, Virginia.

Back to his teleprompter-free self after enduring over a week of criticism from his own party over his attacks against a Hispanic judge, Trump assailed the president's plans to campaign alongside Clinton, the presumptive Democratic nominee, on Wednesday in Wisconsin.

"We have a president that doesn't know what the hell he's doing, folks," Trump said. "I hear he's going to take a lot of time, during our time, when he's supposed to be looking at trade and the military and all of these things, and he's going to campaign for Crooked Hillary."

"You know what? That's OK. That's OK," Trump said before then issuing a veiled threat to the president. "Because if he does that, we're allowed to say things about him that normally we wouldn't bring up. Remember when Bill started campaigning?"