U.S. stocks fell on Thursday amid concerns over the future of President Donald Trump's agenda, but former Wal-Mart US CEO Bill Simon told CNBC he believes some sort of tax reform will still get done.
Republicans will give it the "very best effort they can," he said in an interview with "Closing Bell" on Thursday.
"They're going to come together and come to a point where they're going to take whatever it is they can get."
James Pethokoukis, economic analyst at the American Enterprise Institute, agrees.
"Republicans at this point are going to focus on getting tax reform or die trying," he told " Closing Bell ."
"Paul Ryan is going to push hard to get something done on taxes," he added.
Trump 's recent comments on the deadly white supremacist rally in Charlottesville, Virginia, have led to worries about whether Congress will work with him to pass his agenda.
On Thursday , the Dow Jones industrial average (Dow Jones Global Indexes: .DJI) fell 274.14 points, or 1.2 percent, for its biggest drop since May 17, to close at 21,750.73.
Since the rally over the weekend, the president has made several remarks that have ignited controversy . During a news conference on Tuesday, he reiterated his initial claim that "both sides" were to blame for the violence that left one person dead and several others injured.
That spurred CEOs to disband Trump's Strategy & Policy Forum on Wednesday. Several executives also quit the president's Manufacturing Council before Trump dissolved it.
Trump is also facing mounting criticism from his own party.
On Thursday, Republican Sen. Bob Corker said , "The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful ... And we need for him to be successful."
Simon applauded those who spoke out against Trump, but said everyone still needs to work together to get tax reform and other business-friendly policies enacted.
"We've got to engage. We have very, very difficult issues that need to be solved in this country and I really encourage people to come back to the table, as difficult as that might be," he said.
The defections are concerning because they leave the president with fewer people to rely on during a time when we're not in a particularly stable global environment, Simon noted.
"If the top talent, the good people, the ones that are rational and reasonable that can help move the president's agenda along disengage, you're left with this insulated group around the president," he said.
— CNBC's Fred Imbert and Jacob Pramuk contributed to this report.
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