Democrats may take control of the House and Senate in 2018 elections because of Americans' views toward President Donald Trump, Wall Street superstar Byron Wien told CNBC on Wednesday.

"Almost everyone thinks that the Democrats have a good chance of taking the House," said Wien, vice chairman of Blackstone's Private Wealth Solutions group. "I think they have a good chance of taking the Senate as well."

It's one of Wien's his 10 predicted surprises for 2018. In his annual note, Wien said voters feel disappointed that Trump has not kept many of his promises and there's a growing "negative reaction to his endless tweets."

Wien, a 50-year veteran of Wall Street, said Wednesday he ruled out a scenario in which Trump gained Republican seats in the House, where Republicans hold 239-193 edge.

"I rejected it because I do think the reaction of the American people is pretty negative toward him," Wien said on "Squawk Box." Trump has a popularity rating below 40, he added.

Democrats are optimistic about their chances in the 2018 midterms because of Republicans' failed efforts to kill the Affordable Care Act and Trump's falling approval rating in 2017. Democrats were also riding on Doug Jones' win in the special Senate election in Republican stronghold Alabama. Jones is being sworn in Wednesday, leaving the GOP with only a 51-49 seat edge in the Senate.

Wien acknowledged that the U.S. economy's recent improvement and the GOP's new tax law could offset some of the Democratic gains, but he believes the run-up to the Nov. 6 elections will work against Trump.

"There are going to be a lot of events between now and November," Wien said. "And I think they're going to work against him."