A perfect storm of scandals, political gridlock, natural disasters, and internecine feuds appears to be taking its toll on Donald Trump, alienating even key constituencies within the president’s hardline base. Trump has battled historically low popularity since he took office, but recent events seem to have eroded his support further, according to a new Fox News poll. Nine months into his presidency, just 38 percent of voters approve of the president, a new low in surveys conducted by Fox.

A remarkable 83 percent of Republican voters still approve of Trump, compared to just 7 percent of Democrats. But while his overall support among conservatives has remained steady, Fox News also found that the president’s support among two critical demographics is slipping—which could portend serious problems for the president and the G.O.P. in 2018 and 2020. Among white evangelical Christians, Trump’s approval rating slipped to 66 percent from 74 percent last month. His support among white men without a college degree dropped a whopping 12 points, to 56 percent. During the 2016 election, white evangelical Christians and working-class white men overwhelmingly voted for Trump over Hillary Clinton—by 80 percent and 71 percent, respectively, according to Fox News.

Republican lawmakers have mostly stuck by Trump, with a few exceptions, voting for his agenda nearly in lockstep. But the Trump-G.O.P. agenda hasn’t proved particularly popular. Trump’s approval is underwater on his handling of health care, North Korea, Iran, the economy, and taxes, according to the Fox News poll. Other recent polls have showed anemic Republican support for the party’s tax-reform plan, which Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan have described as must-pass legislation. While the president remains more popular than Republican leadership, his dwindling support among voting blocs that were key to his ascension could encourage more dissent on Capitol Hill, potentially jeopardizing his already stalled agenda.

With support for the president wavering, a failure to deliver on tax reform could be a tipping point. The vast majority of Republicans in Congress have stood by Trump in the wake of several high-profile defections in the Senate (John McCain, Bob Corker, Jeff Flake), but many made it clear that their support is contingent. “I’m focused on results, and that’s why I’m here,” Lindsey Graham said. “I’d rather not be a constant critic. I’ll stand up when I need to, but I’m trying to get taxes cut.” McConnell echoed the sentiment. “There’s a lot of noise out there,” the Kentucky lawmaker said Tuesday. “Tax reform is what we are about.”