Donald Trump may be losing his core audience, with a new poll finding that his approval rating is plummeting among a normally key group — loyal viewers of Fox News.

A new poll from Suffolk University found that Trump is quickly losing favorability among people who say Fox News is their most-trusted news network. In the poll from June, Trump enjoyed a 90 percent favorability among this group, but in the latest poll that number fell all the way to 58 percent.

That will likely come as a major blow to Trump, who has often praised Fox News while lambasting other networks like CNN and NBC. Though the 58 percent is still higher than the roughly 37 percent who approve of Trump in an aggregate of polls from FiveThirtyEight, it shows that Trump’s popularity is falling even among his once-core base and could spell trouble for Republicans as midterm elections approach next year.

The drop comes after one of the most stinging losses for Trump’s presidency. The president threw his full support behind Alabama Senate candidate Roy Moore even as Moore faced several allegations that he pursued inappropriate relationships with young teenagers when he was in his early 30s. Moore decried the allegations and Trump stood behind him, but Moore suffered a shocking loss on Tuesday to Democrat Doug Jones.

A report from the Washington Post noted that Donald Trump felt stung by the loss and tried to mitigate his own blame, with a senior adviser saying that Trump boasted, “I won Alabama, and I would have won Alabama again.”

Trump’s support among Fox News viewers plunges 32 points in stunning new poll https://t.co/oFOQG0mvFL via @shareblue — Oliver Willis (@owillis) December 15, 2017

During the past several months Trump has found his way into a number of controversies, from criticism of protesting NFL players to support of an unpopular health care legislation to a hesitancy to condemn white supremacists at a rally that left a counter-protester dead. In that time Trump has scored only one major legislative victory, but it comes with a tax overhaul that remained largely unpopular in approval polls.

Donald Trump has been a loyal viewer of Fox News himself, and reportedly starts each day by watching Fox & Friends. Trump frequently tweets about topics that the show raises, often within minutes of them airing on Fox News.