Former Trump White House adviser Peter Navarro on Monday recommended former President Trump put more focus on contrasting his policy differences with Vice President Harris, rather than repeated personal attacks.

"He needs votes, and the current rally formula is simply not sufficiently focused on the very stark policy differences — policy differences — between him and Kamala Harris that will swing voters in key battleground states," Navarro said Monday while filling in for host Steve Bannon on his "War Room" podcast.

"Instead, when Trump attacks Harris personally rather than on policy, Harris’s support among swing voters rises, particularly among women. It’s just a fact of life, right now," he added.

Harris replaced President Biden at the top of the Democratic presidential ticket in late July and has since bolstered energy in the party's base and seen a surge in the polls against Trump. Her battleground state rallies last week drew thousands of individuals.

She has managed to narrow the lead Trump maintained when Biden was still in the race and a Decision Desk HQ polling aggregation Monday showed the vice president with a 0.4 percentage point lead over Trump, the official Republican presidential nominee.

In a poll from The New York Times/Siena College released last Saturday, Harris was up 4 points on Trump in the three battleground states of Michigan, Wisconsin and Pennsylvania. This marked a significant shift from Biden's numbers in the same swing states.

Trump has largely brushed off the uptick in support for Harris, arguing it is a "honeymoon period" that will end eventually.

During a press conference last week, Trump criticized Harris as "incompetent" and repeatedly bashed her intelligence.

On Sunday, he accused the Harris-Walz campaign of faking "massive crowd sizes" using artificial intelligence, but he did not provide any evidence.

Republican pollster Frank Luntz made a similar argument to Navarro's over the weekend, suggesting that while Trump has the issues on his side, his "persona" is contributing to the former president's drop in the polls.

“If it’s about issues, Trump is much more likely to be successful. If it’s about attributes, Harris is much more likely to be successful, because quite frankly, people like her more than they like him. It’s something that, if he’s watching this right now, his head is exploding — and that’s part of the problem,” Luntz said over the weekend in a CNN interview.

“He has lost touch with the people that he needs, and she is in perfect touch,” Luntz added, pointing to the bolstered energy during Harris’s recent campaign rallies.

Navarro was released from federal prison last month after serving a four-month sentence for refusing to comply with a congressional subpoena related to the Jan. 6 attack on the Capitol.

Bannon, the onetime adviser of Trump, reported to prison last month to begin his four-month sentence for two counts of contempt of Congress. Like Navarro, Bannon also defied a subpoena from the House committee investigating the Jan. 6 insurrection.