I struggle with the volume of coverage that’s produced every time a Republican announces, or even teases, a primary challenge to President Trump. On one hand, it was notable that former Illinois Rep. Joe Walsh threw his hat into the ring this week, as he is a former Trump supporter of some stature (after leaving Congress, he became a nationally syndicated radio host). On the other, covering Walsh and his ilk as serious candidates implies that Trump is actually vulnerable to a primary challenge, and, well … he’s not.

There are plenty of reasons a primary challenge to Trump will probably fall flat. For starters, serious primary challenges are fairly rare; the last sitting president to be denied renomination was Chester Arthur in 1884. (Yes, there was Lyndon Johnson, but he retired before he could properly lose the nomination — although primary challengers probably had something to do with his decision.) Putting that aside, however, the biggest thing Trump has going for him is that he is extremely popular among Republicans — and that’s true in virtually every poll. For example, 88 percent of the GOP approves of his job performance in the latest Gallup poll. (True, Trump approval isn’t quite that high among voters who merely lean Republican, but even polls that incorporate leaners still give him overwhelming intraparty support — 82 percent in one recent poll.)

According to a CNN analysis from December, the only president in the last 70 years who was more beloved among members of his own party (as measured before the New Hampshire primary) was Dwight Eisenhower in 1956. And this is important because the only presidents who faced muscular primary challenges in the modern primary era were all under 75 percent approval with members of their own party: Gerald Ford in 1976, Jimmy Carter in 1980 and George H.W. Bush in 1992. And yes, all three went on to lose the general election. This is not to say that primary challenges caused those losses; it could just be that only weak incumbents draw primary challengers. Trump is currently not weak among members of his own party (although he is unpopular overall), so it’s unclear if his primary challenges will foreshadow that same result.

Finally, head-to-head polls of the Republican primary give Trump massive leads over any primary challengers. He leads former Massachusetts Gov. Bill Weld, who was the first notable candidate to jump in the race, by anywhere from 60 to 85 points, and he even leads high-profile hypothetical challengers like Utah Sen. Mitt Romney and former Ambassador to the United Nations Nikki Haley by up to 80 points.

But these stubborn facts don’t appear to be deterring challengers — though it’s probably not a coincidence that those who might run are former politicians with no current office to lose. In addition to Walsh and Weld, former South Carolina Rep. Mark Sanford is considering jumping in. But beating Trump may not be their real goal (Sanford, for example, has acknowledged that it would be close to impossible); instead, they may simply be hoping to spur a conversation about the party’s direction. Earlier this year, my colleague Geoffrey Skelley devised a scale for rating the “success” of presidential primary challengers on this front, from 1 (no-name candidates) to 5 — the (as-yet hypothetical) candidate who manages to successfully topple a sitting president. Right now, I would think that Walsh, Weld and potentially Sanford are somewhere between Levels 1 and 2. They are known commodities and could put together a professional campaign apparatus, but it seems unlikely that they will attract as much support as Pat Buchanan did against Bush in 1992, the model for a Level 2 primary challenge.

But of course, we can’t give them a final grade until after the primary. It will be interesting to see if one of the three is more successful given that they each represent different wings of the party: Weld is a socially liberal New England Republican; Sanford is a fiscal hawk in the wonkish ideological mold of former House Speaker Paul Ryan. And Walsh is a former tea partier who actually shares some of Trump’s controversial stances — for example, he called former President Barack Obama a Muslim and an “enemy of the state,” although he has since said he was wrong for doing so.

So someone like Weld may be best positioned to appeal to the most Trump-skeptical Republicans: those who are liberal or moderate, live in urban or suburban areas, are younger and/or identify as independents. On the other hand, Walsh’s in-your-face style may be needed to actually pry away some of the president’s existing support. Then again, maybe Sanford may hold the most appeal to business-oriented Republicans (and their deep pockets), who have traditionally made up the Republican establishment.

At the same time, if there is only a limited amount of anti-Trump sentiment in the party to go around — say, 10 or 20 percent, based on the polls — there is the risk that Republican challengers split that small share into even smaller pieces, rather than eat more into Trump’s support. For example, a HarrisX national poll from May, when Trump and Weld were the only notable Republicans in the race, gave Trump a 73-7 lead. But HarrisX’s latest national poll, the first to include Walsh, puts Trump at 76 percent, Walsh at 5 percent and Weld at 3 percent. So any additional candidates who jump into the race saying they want to “stop Trump” may make it harder to do just that.

That said, even if the president doesn’t lose renomination, it would still be a bad sign for Trump if one of his challengers gets frisky and siphons off a respectable share of the primary vote. It would put him in a category with Ford, Carter and Bush, which would bode poorly for his reelection chances. Realistically, that may turn out to be the most important takeaway from Walsh’s and other primary challengers’ campaigns.