Rand Paul Chip Somodevilla/Getty Images Sen. Rand Paul of Kentucky suggested Monday he was dissatisfied with nine-page plan for tax reform released by President Donald Trump and "Big Six" tax negotiators.

Paul cited an analysis by the Urban-Brookings Tax Policy Center that showed that taxes for a slew of middle-class Americans could increase over 10 years under the new framework.

"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 tweeted along with a link to the TPC analysis.

According to the report, the elimination of certain deductions — in favor of doubling the standard deduction — would eventually cause taxes for many people to increase.

"By 2027, taxes would rise for roughly one-quarter of taxpayers, including nearly 30 percent of those with incomes between about $50,000 and $150,000 and 60 percent of those making between about $150,000 and $300,000," said the TPC report.

Paul became the second Republican senator to publicly express doubts about the plan. Sen. Bob Corker of Tennessee said Sunday that if it looked like the plan was "adding one penny to the deficit, I am not going to be for it."

The Kentucky senator already bucked the GOP leadership over recent attempts to repeal and replace the Affordable Care Act, arguing the legislation from the party did not go far enough in stripping away regulation in the healthcare market.

It now appears Paul could become a thorn in the leadership's side on a second straight major legislative push.