Republican leaders and tax writers are coming under increasing criticism over both the substance and process of their tax overhaul measure, and they are beginning to push back. 

In a somewhat testy GOP leadership press conference Tuesday morning, Speaker Paul D. Ryan defended his team’s handling of not just the current legislation, but other measures that will, like the tax bill, come to the floor under a closed rule, thereby limiting members’ opportunities to change it.

“Absolutely we have an open process,” the Wisconsin Republican said when asked about his pledge upon becoming speaker to open up the legislative process — and the Rules Committee reportedly breaking a record for number of closed amendment rules adopted.

Ryan said bills are going through the committee process and defended the closed amendment process on the floor as a way to prevent “dilatory tactics.”

“We also don’t want to have amendments that are designed to stop this process,” he said.

Watch: Rep. Reed Stacks Tax Code Books at Markup

Meanwhile, House Ways and Means Chairman Kevin Brady, R-Texas, spent most of an interview with radio host Hugh Hewitt defending provisions that are in the bill, like limiting the mortgage interest deduction for new homes to interest paid on the first $500,000 of principal, repealing the state and local income tax deduction, the bill’s effect on small businesses’ pass-through income and repealing the adoption tax credit.

The chairman offered no signal that he was willing to change any of those provisions.

Brady, a father of two adopted children, said he doesn’t think the current credit is effective, saying, “It doesn’t help a lot of families.”

House Minority Whip Steny H. Hoyer told reporters Tuesday morning that  the tax overhaul bill is still changing but he expects “overwhelming” Democratic opposition.

“I think that the Democratic Party is going to be united,” he said.

“This is not a serious attempt and certainly not a bipartisan [attempt],” the Maryland Democrat added.

Across the Capitol, Hoyer’s message was buttressed by Senate Minority Leader Charles E. Schumer who used his leadership remarks to criticize the tax legislation as a hike on the middle-income taxpayers. 

“Record speed, no hearings, no real discussion. And unfortunately, Senate Republicans are mimicking the House in trying to rush through their bill as well,” he said.

Watch: Rep. Larson’s Fiery Condemnation of Tax Bill Process

He criticized Senate Majority Leader Mitch McConnell and other Republicans for saying that “nobody in the middle class is going to get a tax increase under the Republican bill.”

“If Leader McConnell was referring to the House bill, that’s just a bold-faced lie, and he ought to retract it. But, to give my friend the benefit of the doubt, maybe he’s referring to the Senate tax bill still under consideration. Let’s see. In the Republican bill, will nobody in the middle class get a tax increase? We’re waiting and seeing,” Schumer said.

During his own leader remarks, McConnell said the Senate Finance Committee is preparing to engage on the issue, with Finance Chairman Orrin G. Hatch of Utah preparing to unveil legislation as soon as this week. “Chairman Hatch will continue to lead the committee through an open process, giving members the opportunity to provide their input, offer amendments and work together to take another big step forward,” McConnell said.

Lindsey McPherson and Jael Holzman contributed to this report.