Newt Gingrich said it's his hope that President Donald Trump remains presidential and doesn't "pick a fight" with Arizona's Republican senators during his rally in Phoenix on Tuesday night.

With Trump coming off an exceptional speech to the American people in primetime Monday night, the former House speaker turned Fox News analyst said the rally will be must-see TV.

"It'll be fascinating to watch because he's clearly in transition," Gingrich said Tuesday on Fox News' "America's Newsroom." "Does he go back to a much more divisive, angry rhetoric tonight, or does he stick with this presidential style which last night gave him enormous positives?"

"My hope would be that he sidesteps Sens. (John) McCain and (Jeff) Flake; he's going to need both of them this fall, in terms of the agenda. This is not a place to pick a fight," Gingrich continued. "And I hope he will be more presidential and less confrontational, but look, he is the president and gets to do what he wants."

Both McCain and Flake have been hyper-critical of Trump over various issues since Day 1, with Flake an outspoken member of the Never-Trump Republicans. Flake's approval rating in his own state hovers around 18 percent.

McCain infamously sunk a core Trump initiative by voting against the skinny repeal of Obamacare, and he has been vocal in his criticism of Trump's administration when it comes to Afghanistan. However, he did praise the president's revamped vision for Afghanistan during his speech Monday night.

Gingrich said the rally is an opportunity for Trump to stay close to his base.

"I think he keeps faith with his base, reminds them that he's still committed to controlling the border; gives him a chance to tell them that illegal crossings are down 76 percent," Gingrich said on Fox News.

But what will Trump ultimately say or do Tuesday night? Gingrich has no idea.

"I wrote 'Understanding Trump,' I didn't write 'Predicting Trump,' because I don't think it's possible," Gingrich said.

"I think all of his advisers are going to say, 'Please focus in a positive way,' but when the audience starts reacting and he starts getting excited, who knows what's gonna happen?" Gingrich said.