The partial government shutdown is beginning to drag on President Trump’s approval rating, which is at its lowest point in months. As of early Wednesday evening, his approval rating was 40.2 percent, according to our tracking of public polling, down from 42.2 percent on Dec. 21, the day before the shutdown began. It’s his lowest score since last September. And Trump’s disapproval rating was 54.8 percent, up from 52.7 percent before the shutdown. His net approval rating, -14.6 percent, was at its lowest point since February 2018.

There shouldn’t be much doubt that the shutdown is behind the negative turn in Trump’s numbers. While there have been other newsworthy events over the past few weeks, such as turnover among Trump’s senior staffers and a wobbly stock market, the shift is well-timed to the start of the shutdown on Dec. 22. Trump’s approval ratings had been steady at about 42 percent for several months before the shutdown. Since then, they’ve been declining at a fairly linear rate of about half a point for every week that the shutdown has been underway, while his disapproval rating has increased by half a point per week. Trump’s increasingly negative ratings match polling showing Americans growing concerned about the shutdown and disliking Trump’s handling of it. In a Marist College poll that was released this week, for example, 61 percent of respondents said the shutdown had given them a more negative view of Trump, while just 28 percent said they felt more positively toward him.

So all of that sounds pretty bad for Trump. But will any of it really matter to Trump’s political standing, in the long run?

The glib answer is “probably not.” We’re a loooong way from the presidential election. And presidential approval ratings, as well as those for congressional leaders, typically rebound within a couple of months of a shutdown ending. A shutdown in October 2013 that caused a steep decline in ratings for congressional Republicans didn’t prevent them from having a terrific midterm in 2014, for instance.

Also consider the insane velocity of the news cycle under President Trump. If the shutdown were to end on Feb. 15, and special counsel Robert Mueller’s report on the Russia investigation were to drop the next day, would anyone still be talking about the shutdown?

Moreover, there hasn’t been that much of a shift, so far. In the context of the narrow historic range of President Trump’s approval ratings, which have rarely been higher than 43 percent or lower than 37 percent, a 2-point shift might seem relatively large. But it’s still just 2 points, when many past presidents saw there numbers gyrate up and down by 5 or 10 points at a time.

But I wonder if that answer isn’t a little too glib. There are some reasons for Trump and Republicans to worry that the shutdown could have both short- and long-term downsides.

For one thing, there’s no particular sign that the shutdown is set to end any time soon. And if the decline in Trump’s approval rating were to continue at the same rate that it has so far, it would take his political standing from bad to worse. By Jan. 29, for example, the day that Trump was originally set to deliver the State of the Union address before House Speaker Nancy Pelosi disinvited him from addressing Congress, his approval rating would be 39.3 percent, and his disapproval rating would be 55.9 percent. By March 1, at which point funding for federal food stamps could run out, his approval rating and disapproval rating would be 36.9 percent and 58.4 percent, respectively, roughly matching the lowest point of his presidency so far.

In addition, because this is already the longest shutdown in U.S. history, past precedent for the political impact of shutdowns may not be fully informative. There’s the possibility that the shutdown ends not with a whimper (with Trump caving or with he and Pelosi anticlimactically reaching a compromise) but instead with a literal or proverbial bang, such as the government bungling a response to a natural or man-made disaster.

A prolonged shutdown could also materially affect the economy, although there could be some catch-up growth later. A temporary decline in GDP or consumer confidence probably wouldn’t affect Trump’s re-election, although a long-term decline obviously would.

Despite those possibilities, I’d still put a lot of weight toward our historical priors, which contain relatively good news for Trump. With almost 22 months to go until the election, it’s too early for either approval ratings or economic data to be highly predictive of a president’s re-election chances. Furthermore, approval ratings tend to rebound after shutdowns, and in any event, the decline in Trump’s numbers hasn’t been all that large, yet.

Nonetheless, if I were hoping for Trump’s re-election, there are two indirect reasons that the shutdown and its fallout would worry me. One has to do with his relationship with the congressional GOP; the other with his strategic posture toward his re-election bid.

The shutdown may have frayed Trump’s relationship with Republicans in Congress

Republican leaders in Congress didn’t want the shutdown in the first place. Senate Majority Leader Mitch McConnell and former Majority Whip John Cornyn originally thought they’d talked Trump out of shutting down the government — “I don’t know anybody on the Hill that wants a shutdown, and I think all the president’s advisers are telling him this would not be good,” Cornyn told Politico on Dec. 18 — before Trump shifted strategies in response to right-wing pressure.

Meanwhile, two of the most vulnerable Republican senators — Colorado’s Cory Gardner and Maine’s Susan Collins — have called for an end to the shutdown. Another, North Carolina’s Thom Tillis, has called for a compromise with Democrats on the border wall and DACA, a deal that the White House rejected last year.

So it isn’t entirely surprising that Republicans in both the House and the Senate have starkly and sometimes sarcastically critiqued Trump’s shutdown strategy.

Congressional Republicans are not a group Trump can easily afford to lose. They have a lot of power to check Trump’s presidency, from modest measures such as treating his Cabinet nominations with more scrutiny to extreme ones like supporting his impeachment and removal from office. Obviously that’s getting way, way ahead of ourselves, and Trump’s approval ratings remain very strong among Republicans for now. That may constrain how much members of Congress push back against the president. But the conventional wisdom is arguably too dismissive of the possibility of an inflection point. Richard Nixon’s approval ratings had been in the low-to-mid-80s among Republican voters for years, but they suddenly fell into the 50s over the course of a few months in 1973. He resigned in August 1974.

The shutdown has prompted Trump to double down on his all-base, all-the-time strategy

But if Trump wants to get re-elected, his biggest problem isn’t what Republicans think about him; it’s what the rest of the country does.

The lesson of the midterms, in my view, was fairly clear: Trump’s base isn’t enough. The 2018 midterms weren’t unique in the scale of Republican losses: losing 40 or 41 House seats is bad, but the president’s party usually does poorly at the midterms. Rather, it’s that these losses came on exceptionally high turnout of about 119 million voters, which is considerably closer to 2016’s presidential year turnout (139 million) than to the previous midterm in 2014 (83 million). Republicans did turn out in huge numbers for the midterms, but the Democratic base — which is larger than the Republican one — turned out also, and independent voters strongly backed Democratic candidates for the House.

Plenty of presidents, including Obama, Clinton and Reagan, recovered from poor midterms to get re-elected. But those presidents typically sought to pivot or “triangulate” toward the center; we don’t know if the political rebound occurs if the pivot doesn’t. Instead, Trump has moved in the opposite direction. Despite some initial attempts at reaching out to the center, such as in passing a criminal justice bill in December and issuing trial balloons about an infrastructure package, Trump’s strategy of shutting down the government to insist on a border wall was aimed at placating his critics on the right, such as Rush Limbaugh and Ann Coulter, and members of the House Freedom Caucus.

Maybe Trump took some of the wrong lessons from 2016. Trump may mythologize 2016 as an election in which he was brought into the White House on the strength of his base, but that isn’t necessarily why he won. And even if it was, trying to duplicate the strategy might not work again:

Given that, perhaps 2018 is a better model for 2020 than 2016. In the midterms, voting closely tracked Trump’s approval ratings, and he paid the price for his unpopularity. According to the exit poll, midterm voters disapproved of Trump’s performance by a net of 9 percentage points. Not coincidentally, Republicans also lost the popular vote for the House by 9 percentage points.

There’s plenty of time for Trump’s numbers to improve, but for now, they’re getting worse. So while the shutdown’s consequences may not last into 2020, it has been another step in the wrong direction at a moment when presidents have usually pivoted to the center.

CORRECTION (Jan. 25, 2019, 2:10 p.m.): An earlier version of the chart in this article incorrectly described the data it showed. President Trump’s approval and disapproval ratings began with Jan. 1, 2018, not the beginning of Trump’s presidency.