A primary challenger would weaken Trump in general election, says polling editor

President TrumpDonald John TrumpReturn hope to the Middle East by returning to the Iran Deal Government shutdowns tend to increase government spending 'Full Frontal' gives six-bedroom house to group that works with detained immigrants MORE will be weakened in the 2020 general election if he first has to face a challenger during the GOP primary, according to RealClearPolitics Washington bureau chief Carl Cannon.

"These guys, if they get challenged, they soften up the president," Cannon told Hill.TV's Joe Concha in an interview that aired Tuesday on "What America's Thinking."

"To this day, Jimmy Carter blames Teddy Kennedy for losing to [former President] Reagan in that 1980 challenge," he added.

Cannon pointed out that a primary challenge means a president's campaign team needs to fundraise and spend money that would otherwise be designated for the general election.

"These campaigns are tough. You say negative things about the person, so independent voters remember them," Cannon said.

"When George H.W. Bush was running, Pat Buchanan gave him a scare in New Hampshire, but he brought up that taxes issue," Cannon added. "To this day, conservative Republicans will tell you, 'Oh, yeah, he lost on the taxes.' Well, the exit polls didn't show that, but Buchanan softened him up, and [former President] Clinton beat him."

A handful of Republicans, including outgoing Ohio Gov. John Kasich and Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeCorker dodges on Trump primary question The Hill's 12:30 Report – Cohen says Trump knew payments were wrong | GOP in turmoil over Trump shutdown threat | Kyl to resign from Senate at year's end Overnight Defense: Senate bucks Trump with Yemen war vote, resolution calling crown prince 'responsible' for Khashoggi killing | House briefing on Saudi Arabia fails to move needle | Inhofe casts doubt on Space Force MORE (Ariz.), have been floated as potential primary challengers to Trump.

"You don't want to get challenged by your own party," Cannon said. "It is a problem. It is not something you just brush away."

— Julia Manchester