UPDATE (Sept. 8, 2019, 9:55 a.m.): Mark Sanford officially jumped into the 2020 Republican primary on Sunday. He joins former Massachusetts Gov. Bill Weld and former Illinois Rep. Joe Walsh in challenging President Trump.

Mark Sanford, the former congressman and governor from South Carolina, is no stranger to criticizing President Trump. In fact, it was arguably his vocal condemnation of the president’s polarizing rhetoric and protectionist tendencies that cost him his House seat in 2018. But that hasn’t deterred Sanford from considering mounting a primary challenge against Trump. In an interview with Charleston’s Post and Courier last week, Sanford said he will take the next month to think through launching a campaign to start “pushing a national debate about America’s mounting debt, deficit and government spending.”

If he runs, Sanford could be a more attractive option to some Republicans than former Massachusetts Gov. Bill Weld, who announced his primary challenge to Trump back in April, as Sanford’s fairly conservative record is considerably more in line with the GOP. But considering that Trump has already “defeated” Sanford once before — Trump endorsed Sanford’s primary opponent in 2018 in a last-minute tweet, and Sanford lost renomination — the issue isn’t as much about whether Sanford could defeat Trump. Rather, the question is: How much trouble could he cause the president in a primary?

The South Carolinian has had a long political career, featuring two different stints in the U.S. House with two terms as governor sandwiched in between. He even weathered a memorable political scandal — he went missing for a few days in 2009 “hiking the Appalachian Trail” when he was, in fact, in Argentina carrying on an extramarital affair — to win political office again. And during his nearly two decades in office, Sanford built a reliably conservative (albeit somewhat moderate) record. According to VoteView.com, Sanford was consistently one of the more conservative members of the Republican Party during his congressional tenure. As a result, Sanford’s views may fall closer to the Republican mainstream than the socially liberal, economically moderate positions that Weld espouses.

Where Sanford is perhaps most in line with the Republican Party is with his stance on fiscal policy — reduce the deficit now — so if he were to run, this issue would be at the center of his presidential bid. On Wednesday, he even released a video in which he expressed his concerns about America’s fiscal future, arguing that people in Washington “have seemingly forgotten that debt, deficits and spending really do matter.” And Sanford’s record backs up his rhetoric. As a member of the conservative House Freedom Caucus, Sanford slammed the Trump administration’s budgetary plans for making projections based on “a Goldilocks economy” that he viewed as unrealistically bullish. And as governor, he held the line on government spending, refusing to take money for his state from the 2009 federal stimulus package until the South Carolina Supreme Court ruled against him. In theory, Sanford’s views on fiscal policy could garner him some support in the GOP, but then again, fewer Americans now see reducing the nation’s deficit as a top priority.

One other factor that might encourage Sanford to run is South Carolina’s early position on the presidential primary calendar. The “First in the South” contest has voted third (behind Iowa and New Hampshire) in the past two Republican contests and would presumably go early once again in 2020 — if the GOP even has a primary there. South Carolina Republicans have said they might not hold a primary in 2020, but Republican Gov. Henry McMaster has said he would support GOP primary if a legitimate challenger to Trump got into the race. Nonetheless, even if Sanford ran and South Carolina held its primary, Trump is quite popular among Republicans in the state — an April poll from Winthrop University found his approval among Republicans and independents who lean Republican to be 79 percent. That might seem low — Gallup has Trump’s approval among Republicans at about 90 percent — but the inclusion of independent GOP leaners probably explains the difference.

So even if there are some Republican voters who say they oppose Trump or are open to backing a challenger, the percentage who would be willing to support an opponent is too small to seriously threaten Trump’s renomination chances. And that’s because Trump’s approval among Republican primary voters nationally is 85 percent, according to recent data from Morning Consult. Trump is also regularly polling north of 80 percent in head-to-head matchups against Weld. So even if Sanford were a stronger challenger than Weld, it’s hard to see any path to victory — the numbers just aren’t there.

Back in February, we published a “Primary Challenge Success-O-Meter” to rate the danger posed by different types of primary challengers to an incumbent president. Given Trump’s strengths, Sanford would probably be a weak Level 2 challenger, someone who could make a little bit of a splash but never seriously threaten the president’s chances of renomination. Sanford’s goal would probably be to influence the conversation about the future of the GOP, much as Pat Buchanan did during his unsuccessful yet notable challenge to President George H.W. Bush in the 1992 Republican primary.

And arguably, Sanford sees his potential candidacy as about something besides winning. “Sometimes in life you’ve got to say what you’ve got to say, whether there’s an audience or not for that message,” Sanford said in his interview with the Post and Courier, adding, “I feel convicted.”