GRANTVILLE, Pa. — It didn’t take long for Jack Morris to regret voting for President Obama. A few months after Mr. Morris, a lifelong Republican, cast his first vote for a Democrat in 2008, he learned that the carpet company where he worked planned to lay off 36 people in Pennsylvania and move his job to Maryland.

He went home and lamented to his wife that he had made a big mistake buying into Mr. Obama’s message of hope and change. The president had been in office less than half a year, and already the disappointment that would color the next eight years for Mr. Morris was sinking in.

“I just told my wife, ‘I screwed up. I should’ve never voted for him,’” said Mr. Morris, 46, who now supports Donald J. Trump. “I took the chance, left my party to come and try and vote for him to change. It didn’t work, and now I’m back to my party.”

Mr. Morris is one of a small subset of voters who supported Mr. Obama in 2008 and have now embraced Mr. Trump, attracted by his vow to shake up the political status quo and restore lost jobs. A CBS News poll conducted last month found that 7 percent of likely voters who supported Mr. Obama in 2012 now back Mr. Trump, a ray of hope for a candidate who remains behind in most polls and has alienated many centrist voters.