President Donald Trump, often seizing on stock market gains as a personal victory, may now see that he can get on the market’s bad side.

Stocks sold off sharply Thursday, as investors worried about a possible exodus of cabinet members and advisors and doubted his ability to push through pro-growth programs. Rumors circulated that highly regarded White House advisor Gary Cohn was planning to leave, but the White House denied the rumor.

The Dow ended the day down 274 points, to 21,750, its worst day in three months. The S&P 500 was off 1.5 percent to 2,430, its worst day since May. However, it is still up a lofty 13.5 percent since the election.

Dow and S&P 500 futures Friday were flattish, but the Nasdaq was higher. Global markets followed Wall Street lower, and the dollar remained under pressure.

“For the first time, people are now questioning if he can get anything done policy-wise. His agenda is under threat,” said Peter Boockvar, chief market analyst at The Lindsey Group.

Analysts said the market heads into Friday focused on Trump and the continued fallout after he appeared to show support for white nationalists involved in a violent protest in Charlottesville, Virginia, last weekend.

His incendiary comments, which he repeated in an off-the-cuff briefing Tuesday, prompted the departure of CEOs from his advisory councils, and his Strategic and Policy Forum disbanded itself just before he shut it down. Now the concern is that he will have increasing problems finding support among Republicans in Congress.

In a strong statement, GOP Sen. Bob Corker of Tennessee told reporters Thursday that Trump has not shown the “stability” or competence to be “successful.” He noted that the country needs to see Trump succeed. “I do think there need to be some radical changes,” Corker told reporters, according to a video posted by a reporter for Nooga.com.

Stocks looked technically weak, closing at the lows of the session Thursday. The CBOE Volatility Index, the VIX, sometimes known as the fear index, surged 32 percent to 15.55.

“I think it’s Trump-related. People are worried about the unraveling of his team, his administration’s authority and what this means for tax reform. Every day, he makes a new enemy in Congress. Today’s he’s picked a fight with [South Carolina Sen.] Lindsey Graham,” said Boockvar.

Trump also tweeted his support for Confederate monuments, which sent more ripples across the market. A terrorist attack in Barcelona also jangled nerves, amid the sell-off.

“[Friday] is the end of the earnings season. It’s going to be a shift from the micro to the macro, and that’s never good. During the earnings season, the market is feeling like Teflon and nothing matters but earnings,” said Art Hogan, chief market strategist at Wunderlich. But now the market will focus on Trump.

“That’s the biggest overhang in this market right now … it’s a big story that the corporate CEOs are pulling away from this president. It’s not just economics,” said Hogan. He said the big worry is that Republicans will also abandon him.

“He’s touched the third rail on this and nobody wants to be associated with it,” Hogan said. “The only saving grace is even though Republicans don’t want to be associated with him, they don’t want to go into 2018 without tax legislation, or anything, any accomplishment whatsoever.”

Hogan and other analysts expect Congress to continue to push for tax law changes, with or without Trump.

“Maybe the Trump trade is over. But maybe it’s more simply the tax trade and it might not come from Trump,” said Sam Stovall, chief market strategist at CFRA. “Those goals are still out there. They still want them. It’s just the champion will change.”

Stovall said Trump is becoming more isolated. “The big concern was the president would end up isolating us, the U.S., from the rest of the world. Now what we’re finding is the president is isolating himself from the rest of the world,” he said.

Art Cashin, director of floor operations at UBS, said the market had been able to give Trump a pass because it was reassured by his advisors. “The concern would be that if one left maybe several would leave, and that would leave him with no competent people around him,” he said.

Scott Redler, partner with T3Live.com, said Thursday’s market sell-off was significant, and it’s now flashing a warning to reduce risk. He personally moved into cash Wednesday and is now wary of the market, particularly with the weak seasonality that usually comes with August and September.

“This is not a time to be long. But we’ll see if the bears can reassert some power. You had your third lower high in the QQQs and your third lower high on the S&P,” he said. The PowerShares QQQ Trust is based on the Nasdaq 100.

Redler, who follows short-term technicals, said he went into last weekend expecting some selling this week, but the market surprised to the upside Monday, as North Korean fears receded. Those gains have faded, and the S&P 500 fell through 2,450, its 50-day moving average. Redler also said it was an important move when the S&P fell below 2,437, the recent low from last week.

“The next level traders will be eyeing is the 100-day at 2,416, and I don’t think traders will be in much of a rush to buy, because a 3 percent correction, which is somewhat normal, doesn’t happen until 2,390,” he said.

Redler said he expects traders to be cautious Friday, heading into the weekend. There are also options expirations Friday.

“Trump is definitely a headwind. He was a tail wind for the first three to four months. Then he became neutral and now people are losing faith in anything he can do,” said Redler. “If he can’t keep the Manufacturing Council together, how’s he going to get tax reform? There were a lot of traders scratching their heads yesterday about why the market was higher.”

Trump meets with his National Security team at Camp David Friday.

There are a few earnings Friday, including Deere, Estee Lauder and Foot Locker. Deere was down 5 percent after its earnings, and Foot Locker was down nearly 20 percent. There is also consumer sentiment at 10 a.m.

Dallas Fed President Rob Kaplan speaks at 10:15 a.m. ET.