Steve Louro, a Republican donor who hosted an event for Donald J. Trump at his Long Island home last year, abruptly quit his post as regional finance chairman for the state’s Republican Party on Tuesday over objections to the Republican-led tax bill advancing through Congress.

“The bill that’s going to get passed is not going to take care of the American people. It’s a disgrace,” Mr. Louro said in a phone interview. He had resigned from his post as a fund-raiser via email earlier in the day, he said.

“The Republican Party took control of the government against all odds, and the bottom line is” they messed up, he said, using an expletive. “It’s a disgrace. It’s going to hurt a lot of middle-class Republicans.”

The tax legislation has proved particularly contentious in New York, since both the Senate and House versions of the bill would scrap state and local tax deductions. As a result, seven of nine New York Republicans in the House voted against the bill.