Alabama Senate candidate Roy Moore was meant to be "tabasco sauce in the eyeball of Mitch McConnell and the Republican party," Chris Stirewalt said.
"The purpose of Roy Moore had nothing to do with winning the election and keeping the seat Republican ... it was that it was worth it to torture the Republican party," the Fox News politics editor said on "The Daily Briefing" Monday.
The firebrand conservative is unpopular with the establishment GOP for his hardline policies.
Many senators renounced Moore after four women related that he pursued sexual relationships with them when they were teenagers. One was only 14 when she says the then 32-year-old assistant district attorney sexually assaulted her in his home. Moore has denied all allegations.
"Moore ain't going anywhere," Stirewalt predicted. "He's making it clear he's going to burn this mother down."
"For his supporters, the more McConnell says he wants Moore out, the more they want him to stay, and it intensifies that, and he can play on that."
A write-in campaign, which McConnell said he would not rule out, would likely split the Republican vote and hand the race to Democratic candidate Doug Jones, Stirewalt said.