“Let Trump be Trump” was the mantra that guided Donald Trump's successful drive to the Republican presidential nomination. But his team is taking a “Let Hillary be Hillary” approach to the first presidential debate. 

Fox News has learned that the view inside Trump Tower is that the real estate mogul stands to gain by standing back and letting Hillary Clinton talk. And talk. 

Whether it's a wise strategy to give the studied Democratic nominee even more time to show off her policy chops remains to be seen. But the GOP nominee is being advised to let Clinton speak as much as possible on the debate stage, with the thinking being that she could lose viewers the more she does. 

“I think both candidates face huge challenges. Both of them are not well liked by the American people. She's an accomplished debater. But she has a style that is oftentimes grating on people,” said Karl Rove, former adviser to President George W. Bush. 

The Clinton campaign is pursuing its own unique debate approach -- pre-emptively casting Trump as a "habitual liar."

They released a dossier Friday of his biggest "lies" and are trying to make sure the moderator and media hold his "facts" to the fire on Monday.  

“Debates are about each candidate laying out their vision for America, not making things up. Donald Trump has shown a clear pattern of repeating provably false lies and hoping no one corrects him. Voters and viewers should keep track: any candidate who tells this many lies clearly can’t win the debate on the merits,” Communications Director Jennifer Palmieri said in a statement. 

The maneuvers are all part of the campaigns' careful strategizing for what could be the most important moments of the final six weeks: The three debates starting Monday. 

Trump and Clinton have taken a different approach to preparing. Clinton has spent much of the past week hunkering down and hitting the books, while Trump has kept a rigorous campaign schedule. 

Still, Fox News has learned that Republican National Committee Chairman Reince Priebus will be coming to New York Saturday to help Trump with debate preps during sessions at Trump Tower.

Both candidates want to make sure they know the answers to Monday's questions, as they will be challenged to speak to the most pressing issues facing the nation. But in the modern television debate, style matters as much as substance, if not more. 

“[Clinton] will come to the debate armed with a deep knowledge of the issues, but ultimately has to show she can be likeable. She has to come off as dismissive [of Trump’s barbs] but not in a patronizing way,” said Richard Himelfarb, an associate professor of political science at Hofstra University in New York, the site of Monday’s debate.

“The debate is going to be decided on body language, tone and temperament. It will all be about tone and demeanor and much less about substance,” he said. 

In the final days before the showdown, Trump has maintained his busy schedule, including a planned rally in Roanoke, Va., on Saturday.

In contrast, Clinton's last public appearance was on Wednesday. Hoping to show a lighter side, Clinton taped appearances for the comedy show “Between Two Ferns,” and NBC’s “The Tonight Show.”

The campaign may hope to tamp down the frustration that was apparent during a Wednesday televised address to a gathering in Las Vegas of the Laborers' International Union of North America.

“Having said all this, ‘Why aren’t I 50 points ahead?’ you might ask?” Clinton said in the remarks, raising her voice. “Well, the choice for working families has never been clearer. I need your help to get Donald Trump’s record out to everybody. Nobody should be fooled.”

The former secretary of state has held numerous mock debates designed to prepare her for whichever Trump appears on the stage on Monday.

“He can come on with a relatively genteel persona that is calm,” Palmieri told Fox News. “Or he can come in very aggressive and be aggressive in a way that you would not normally see a presidential, you know Republican nominee behave and so we're preparing for either one."

Fox News can confirm that two of the most experienced debate strategists – D.C. lawyer Karen Dunn and former Al Gore aide Ron Klain -- have been overseeing the Westchester County debate prep. Dunn famously told President Obama to "punch" Mitt Romney in the "mouth" after a lackluster debate performance in 2012. 

The Clinton campaign and surrogates meanwhile are trying to get under Trump’s skin by circulating a 19-page list of Trump’s “biggest lies” and another with his “Seven Deadly Lies.” The goal is to prod the media to begin “fact checking” Trump on the issues before the debate, as well as in real-time.

Clinton’s camp also has been relying on the insight of Tony Schwartz, who co-authored “The Art of the Deal” with Trump.

Trump’s son Eric suggested Friday that his father has no plans to change the debate playbook. 

“He’s spending a lot of time studying and he is taking it incredibly seriously. But at the same time you have to be yourself. You have to be true to yourself, you have to be true to your message," Trump said on Fox News

FoxNews.com's Jennifer G. Hickey and Fox News' Peter Doocy, Jennifer Griffin, Doug McKelway, Serafin Gomez and Nicholas Kalman contributed to this report.