(Bloomberg) House Republican tax-writers have become tight-lipped about their schedule for advancing what they’ve called the biggest tax overhaul in three decades.

Rep. Kevin Brady, chairman of the Ways & Means Committee, had said a day after President Donald Trump’s election that he anticipated a tax-law rewrite within the incoming president’s first 100 days in office. House Speaker Paul Ryan set a target in December of getting the overhaul done within the first 200 days of the new administration, which would be before Congress recesses in August.

House Ways & Means Committee Chair Rep. Kevin Brady, R-Texas (right) and Speaker of the House Paul Ryan, R-Wis., at a hearing.
House Ways & Means Committee Chair Rep. Kevin Brady, R-Texas (right) and Speaker of the House Paul Ryan, R-Wis., at a hearing. Bloomberg News

Now, some key lawmakers are demurring on setting a timeline after hitting a few early hurdles. Opposition has sprung up within the Republican Party and amid major U.S. employers to portions of Ryan’s preferred tax plan -- especially a provision to tax U.S. companies’ domestic sales and imported goods while exempting their exports. Meanwhile, lawmakers have made little progress on their goal of unwinding Obamacare, a goal that’s considered the GOP’s No. 1 priority and may also complicate tax legislation.

“We haven’t set any hard and fast dates on timetable yet, either on draft or a committee vote there,” Brady, a Texas Republican, told reporters Monday.

He said only to “anticipate some hearings on tax reform this year.”

“Right now we’re really focused on the elements, the education, the design, the input. We’re listening a lot to lawmakers, to stakeholders, to businesses about the most pro-growth design,” Brady said.

Peter Roskam, the Illinois Republican who chairs the House Ways & Means Subcommittee on Tax Policy, also declined to comment on exact timing during a speech at the Heritage Foundation Monday.

Roskam said that Brady was gathering members to focus on how tax proposals would affect specific issues such as retirement and pass-through entities. He said that drafts of legislation on those topics would be sent to Congress’ Joint Committee on Taxation, which assesses the cost of the measures -- setting the stage for additional discussions.

And while Roskam said that he remains confident that the House plan will prevail, he also said that rewriting the Tax Code is a complex undertaking -- and he suggested the task will rely on skilled coalition-building. “This is not for the faint of heart,” Roskam said.

An association of more than 120 trade groups representing the auto industry and retailers including Wal-Mart Stores Inc. has formed to oppose the House Republican plan -- arguing that its so-called border adjustments would mean taxes on imported materials leading to higher costs for consumers. A rival group that includes such corporate giants as General Electric Co. and Boeing Co. has formed to advocate for the plan, which they say would help U.S. manufacturers compete with overseas producers.

Brady had told CNBC on Nov. 9 that he was optimistic about a speedy tax overhaul because Trump had “made it clear through the campaign that he’s ready to move on the economy.”

When asked on Monday if the slow progress on repealing Obamacare is holding up tax reform, Brady said that Republicans are “running parallel tracks” on the two issues, but added that he’s deferring to Ryan and Trump on timing.

- Sahil Kapur