Donald Trump has a big problem: Even though he has garnered heavy support in the GOP primary, those millions of voters make up a fraction of the electorate likely to vote this fall. And nearly two-thirds of that larger electorate dislikes him.

An NBC News/Wall Street Journal survey earlier this month found that 64 percent of voters disapproved of Trump. They've reached this conclusion after watching Trump on the national stage for decades, combined with the rising vitriol in the current Republican race.

So how could the controversial real estate mogul overcome his own unpopularity? A former Trump adviser says the answer is to make Trump's opponent even less popular.

"He's not running against nobody," Roger Stone said on Morning Edition. "Hillary Clinton, the presumptive Democratic nominee, is exceedingly polarizing herself."

Stone is a consultant and well-known political provocateur who once advised Trump. They parted ways last summer, with Trump saying Stone was seeking too much attention for himself. Stone said he disagreed with some of Trump's statements but remains Trump's friend and passionate supporter.

He is also a cheerful advocate of scorched-earth politics, and that is just what he proposes as a strategy for Trump, if he's nominated.

"While [Clinton's] unfavorables are only in the 50s, that's largely because Bernie Sanders has not attacked her at the point of most vulnerability," Stone said. The eventual Republican nominee could get much dirtier in his attacks than the Vermont senator had, Stone argued.

Stone said Trump could attack Clinton's "tenure as secretary of state," as well as "her husband's sexual history" and what Stone called her "abuse of women." The latter phrase is how Stone describes the criticism of women who said they had had sexual relations with former President Clinton.

To be clear, Stone's words do not come from the Trump campaign itself. But this loyal friend of Trump does outline one scenario for a general election, should it finally pit the two current front-runners against one another.

Is Stone saying that Trump's hope would be to tear down Hillary Clinton?

"That's one way to capsulize it," Stone said. "This will be a slugfest."

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