President Trump violated “rule number one” at his “pseudo campaign event” in the Rose Garden on Tuesday when he attacked presumptive Democratic nominee Joe Biden instead of holding a news conference, former White House Deputy Chief of Staff Karl Rove said on Wednesday.

“Rule number one, if you’re an incumbent president running for reelection, your most powerful presence is as the president of the United States,” Rove, a 360aproko News contributor, told “America’s Newsroom.”

“You have the biggest megaphone, the biggest platform and you have the greatest ability to control the quality and content and direction of your message if you act in that way. Don’t use presidential events as campaign events, try to turn campaign events into presidential events,” he continued.

Rove made the comments one day after Trump veered off-script after announcing new legislation against China to attack Biden over his recent policy proposals – accusing the former vice president of aligning his campaign with Vermont Sen. Bernie Sanders, New York Rep. Alexandria Ocasio-Cortez and other progressive leaders.

“Biden has gone radical left,” Trump said. “There’s never been a time when two candidates were so different.”

Rove pointed out that his news conference turned into a “64-minute-long … pseudo campaign event.”

“The president is stronger when he’s president,” Rove said. “That’s one of the great ironies about a president running for reelection is that they’re always stronger when they focus most of their energy and effort and message on the things that they do as president.”

“Joe Biden’s entire career has been a gift to the Chinese communist party,” Trump said on Tuesday.

“Joe Biden and President Obama freely allowed China to pillage our factories, plunder our communities and steal our most precious secrets,” Trump added.

The Biden campaign later fired back at Trump’s comments, saying: “Today’s statement that was ostensibly supposed to be about China, but there was one topic that President Trump couldn’t seem to get off his mind: Joe Biden, whose name the president invoked nearly 30 times. The whole sad affair says more about Donald Trump than he said about any particular topic.

“The American taxpayer should be reimbursed for the abuse of funds this spectacle represented,” the campaign said, adding that “a real leader” – referring to Biden – spoke earlier in Wilmington.

Trump’s comments come hours after Biden released a $2 trillion plan to boost investment in clean energy and stop all climate-damaging emissions from U.S. power plants by 2035.

Host John Roberts asked Rove, “What are the prospects for the president’s reelection? How does that look now?”

In response, Rove provided “an alternative vision.”

“Let’s say that those things that the president said about Joe Biden are entirely appropriate and good points, but what would have happened if yesterday had been the president focused on what he was doing as president?” he asked.

Rove went to say that later this week Trump could have gone “to a manufacturing facility in Pennsylvania, or Ohio or Michigan and delivered a political talk about his predecessors and what they were willing and unwilling to do.”

He noted that if Trump would have “started out by using his megaphone as president and then followed up by being a candidate,” that message would have been “much stronger.”

“If you successfully get that in your mind that you’re strongest when you’re using presidential events to make news and that you ought to be thinking about how you can turn campaign messages you want into presidential events, you come out of the process stronger,” Rove said.

He then pointed out that Trump is now behind in the polls.

A new poll in the crucial general election battleground state of Pennsylvania shows Biden holding a double-digit lead over Trump among registered voters.

Rove noted that Trump “may be coming back because I think the speech at Mount Rushmore gave him a little bit of a pivot point, but he’s got a long way to go and fortunately he’s got a lot of time to do it.”

He also said that the 2020 election will be “strange” and “unlike any that you or I have seen because of how the coronavirus is going to affect the tempo and the forum and the function of the campaign.”