This seems implausible, but it’s not the first poll to show the race there surprisingly tight. A survey taken last week found Graham up by four. Another taken at the end of May had it tied at 42.

Trump won South Carolina by 14 points in 2016. How can Graham’s seat conceivably be in play?

My first thought upon hearing that South Carolina’s become a Senate toss-up is “Aha, it’s because Trump is dragging Graham down. The president’s popularity has waned even in red states and now Republicans downballot are paying the price.” And that’s true: Trump leads Biden by just five points in South Carolina in this new one from Morning Consult, well off his pace against Clinton.

But in SC as well as in Texas, Kentucky, and Alabama — three states where Republicans lead in their Senate races — he’s running ahead of the downballot candidates. If he were dragging everyone down, you might expect to see some anti-Trump Republicans split their tickets between Biden and Republicans running for lower office. That’s not what’s happening here. Voters in each state are more committed to the president than they are to the Senate nominee.

What’s especially surprising about Graham’s weak showing is that he’s the most loyal Trump sycophant among the three incumbents. Granted, he’ll never fully shed his “soft on immigration” reputation, but he’s worked hard to stay in the president’s and MAGA Nation’s good graces over the past four years. There should be very little reason for a South Carolina Republican to say “I like Trump but I’m not sold on Graham.”

Yet that’s exactly what’s happening, per Morning Consult:

In South Carolina, where the Senate race is effectively tied, Graham is experiencing a similar problem with his own base: The Senate Judiciary Committee chairman trails Trump among likely Republican voters by 11 points, 81 percent to 92 percent. By comparison, Harrison has support from 90 percent of likely Democratic voters, roughly matching Biden’s 94 percent.

Polling in North Carolina, Michigan and Arizona reflected a similar trend, with Republicans nearly united behind the president but less certain about the down-ballot contests.

Trump also scores better with independents (46 percent) than Graham does (41 percent). Is Graham’s challenger, Jaime Harrison, that much more formidable than Joe Biden is or is Trump that much more liked than Graham is? If it’s the latter, why are GOP candidates in other states also running behind the president among Republican voters?

I think it’s a combination of the two. Generally speaking, yes, of course Republicans are more loyal to Trump than to their Senate candidate. He defines the party; voters are emotionally invested in him to a far greater degree than they are in congressional apparatchiks. Many Republican voters don’t pay close attention to Senate business so we’d expect more of them to say “don’t know” when asked if they favor their senator over a Democratic challenger.

But in reddish states like South Carolina, Kentucky, and Alabama, I think it’s also true that the Democratic Senate challengers are more “formidable” than Biden is, in one very important sense. They’re spending money to compete aggressively in those states whereas Biden, for the most part, has conceded them. South Carolina arguably isn’t worth a dime of his money since no one expects it to be a tipping-point state in November; if he wins it, it’ll only be because he’s en route to a landslide nationally that’ll deliver the presidency to him anyway. He’s not going to waste much time or money there. Graham’s challenger, Jaime Harrison, is competing aggressively, though, sitting on a massive war chest funded by Democratic donors across the country who hate Graham for his Trump toadyism and want to see him ousted. Harrison’s ad dollars presumably have chipped away just enough Republican and independent support from Graham to make a race of it. That’s less true in Kentucky, Alabama, and Texas, but even in those states Democratic ad spending in Senate races has managed to soften up Republican support to some degree.

The one state of the four where Biden is competing, Texas, also happens to be the one state where he’s leading and is considerably overperforming the Democrats’ Senate candidate. Which raises a question for his campaign: Given how close Harrison is to Graham and how slender Trump’s lead over Biden is right now in South Carolina, should he think about allocating a few more resources there? If he can cut into Trump’s lead in SC the way he’s cut into it in Texas, he might boost local turnout just enough to drag Harrison over the finish line, even if he ends up losing the state to Trump himself.

The good news for Graham, though, is that at the moment it looks like he has more room to grow than Harrison does. Assuming that Biden’s 44 percent is the de facto Democratic “ceiling” in South Carolina unless and until Team Joe starts spending there, presumably some of the Trump supporters who are undecided about Graham right now will come home to him by November. He’ll probably end up winning by five points or so, which isn’t impressive in a state as red as South Carolina but could be worse in a national climate as blue as this one.