A Republican tax reform bill was approved on Thursday to advance to the House floor for a vote, one of several steps needed to achieve the goal of getting a bill on the president’s desk by Christmas. House Majority Leader Kevin McCarthy said the full house will vote on the legislation next week.

Meanwhile, the Senate dropped a bombshell on the process Thursday, breaking with Trump and the House to delay a proposed corporate tax cut until 2019, according to GOP Senator Bill Cassidy. The proposed House bill, in contrast, proposes a gradual reduction in the corporate rate from 35% to 20%, while Trump has said wants the cut to be effective immediately.

The Senate plan also does not propose to repeal the estate tax, though it would double the estate-tax exemption.

In order for legislation to ultimately be sent to the White House, the Senate version, expected to be released Thursday — if passed — would have to be reconciled with any House plan.

US stocks fell after the news of the delay on the corporate tax cuts, and amid the general uncertainty regarding the tax legislation, seeing their worst session in two weeks.

Despite the market reaction to today’s headlines, many still expect the GOP will eventually succeed at passing tax legislation in some form as political pressure grows. Republican lawmakers are not only facing the prospect of primary challenges under pressure from the Republican base, but also saw the erosion of some support among moderates in state electoral defeats this week.