The head of the most conservative faction of House Republicans said he will not vote for tax reform legislation if the corporate rate is not lowered to a maximum of 20 percent.

"If the corporate rate is above 20 percent and if the small business rate is above 25 percent I would vote against it," Rep. Mark Meadows, R-N.C., told reporters at a conservative forum.

Meadows is head of the House Freedom Caucus, which is comprised of about three dozen GOP lawmakers. The group's support for tax reform is pivotal because if they vote together they have the power to sink legislation that lacks any support from Democrats.

Republican leaders will reveal the tax plan, formulated by the Trump administration and GOP leaders, at a GOP retreat Wednesday.

Meadows said his "red line" on tax reform does not represent the rest of the Freedom Caucus, but it's likely to be followed by others.

Rep. Dave Brat, R-Va., for instance, told the Washington Examiner that he backs a maximum 20 percent corporate tax rate as well.

Brat said he would support the GOP "Better Way" tax cut plan, which lowers the corporate tax rate for 20 percent, or the tax plan already proposed by Trump, which would lower the business tax rate to 15 percent.

Meadows said his support also hinges on the tax reform plan doubling the standard deduction for individuals. He also wants the plan to include reformulating the rates for repatriating overseas businesses so their liquid assets and invested earnings are taxed at different levels.

Meadows said the priority for tax reform should be lower rates. He said he has spoken to President Trump about the forthcoming tax plan and he doesn't believe taxes will go up on any bracket, including the wealthy.

But the focus of tax reform will be on reducing rates for "the hard working taxpayer."

"I don't anticipate the upper brackets increasing," he said. "Quite the opposite from what I'm hearing."