Sen. Ron Johnson, a Wisconsin Republican, says he's opposed to the revised Senate GOP tax plan because it doesn't do enough to help partnerships, limited liability companies, S-corps and other pass-through businesses.

"It doesn't really address the core problem as I understand it," Johnson said. "We're moving in the wrong direction."

Johnson said his main concern is that the corporate rate will be slashed to 20% from 35%, while the top pass-through rate won't fall as much. He said he's frustrated that the Senate proposal doesn't slash the top pass-through rate to 25% — as was outlined in the framework released by the White House and congressional leaders in September — and ultimately will make pass-throughs less competitive compared to corporations.