Sen. Rand Paul (R-Ky.) on Monday criticized the tax-reform framework released last week by Trump administration officials and congressional GOP leaders after a think tank issued a report finding that many middle-class taxpayers could see their taxes go up.

“This is a GOP tax plan? Possibly 30% of middle class gets a tax hike? I hope the final details are better than this,” Paul said in a tweet that included a link to the study from the Urban-Brookings Tax Policy Center (TPC).

The TPC’s analysis found that by 2027, almost 30 percent of taxpayers with income between about $50,000 and $150,000 would see their taxes increase under the framework that the White House and congressional GOP leaders released last week.

In total, about 25 percent of taxpayers would see higher taxes under the GOP’s plan by 2027, TPC said.

The chairmen of the congressional tax-writing committees have taken issue with the TPC’s report, criticizing the assumptions the paper’s authors used.

“This so-called study is misleading, unfounded, and biased. TPC makes a variety of overreaching and unrealistic assumptions about policy decisions Members of Congress still have to make as we draft pro-growth tax legislation,” House Ways and Means Committee Chairman Kevin Brady (R-Texas) said in a statement.

The tax framework is designed to provide guidelines for the tax-writing panels as they write legislation.

The plan would collapse the current seven individual brackets to three, of 12 percent, 25 percent and 35 percent. It also leaves the door open for an additional rate above 35 percent for the wealthiest taxpayers. Additionally, the plan calls for nearly doubling the standard deduction and expanding the child tax credit while eliminating most itemized deductions.