Congressional Republicans are pressing forward with plans to repeal President Barack Obama’s health-care law and remake the sprawling U.S. tax code, with the next step on the Affordable Care Act expected this week.

In both cases, the GOP is aiming to use what’s known as budget reconciliation to make huge policy changes. Reconciliation is a tactic allowing lawmakers to fast-track legislation, generally dealing with spending or revenue. In the Senate — which Republicans now control with 52 votes — a reconciliation bill takes just a simple majority to pass. For many other bills, a 60-vote threshold is required to limit debate and move to final passage.

In the case of the health law commonly known as Obamacare, Republicans would repeal much of it through that simple majority vote. Tax policy would be changed under the same process, Senate Majority Leader Mitch McConnell has said. Congressional Republicans and President-elect Donald Trump are both seeking significant tax cuts for corporations and individuals.

But it’s Obamacare that Republicans are setting their sights on first. After a meeting with House Republicans last week, Vice President-elect Mike Pence said “the first order of business is to repeal and replace Obamacare.”

Read:Pence, Obama rally troops in Congress as Obamacare showdown looms.

To that end, the Senate is gearing up to vote on a budget resolution this week. If it passes, which is expected, two Senate and two House committees would have until Jan. 27 to write bills repealing major parts of Obamacare. The resulting reconciliation bill would require a simple majority to pass the narrowly divided Senate. The House, where Republicans have a bigger majority, has voted numerous times to throw the law out.

Analyst Chris Krueger of Cowen and Company said in a note Obamacare would likely be repealed by the second quarter of the year.

Repeal doesn’t mean replacement, however. Republicans have reportedly discussed a delay for repeal of two to four years, giving them ample time to work on a replacement. Asked about a replacement on CBS’ “Face the Nation” on Sunday, McConnell said “we will be replacing it rapidly after repealing it.” He did not offer a definitive time frame, however.

McConnell’s remarks came after a week that saw skittishness among some GOP senators about repealing Obamacare without detailing a replacement. Bloomberg reported Friday a fourth senator has voiced doubts about the party’s strategy.

Also read: Obama challenges Republicans to show their health care plan.

At the same time they are working on a new health-care plan, Republicans and Trump will try to push a tax-code overhaul through Congress. There are many similarities between the incoming president and Republicans’ tax plans, but also some disagreements, such as over Trump’s threats to slap border taxes on companies that leave the U.S. and export their products back to American shores.

As with Obamacare, congressional Republicans are planning to use the same reconciliation process to enact tax changes. McConnell outlined that plan to reporters last month.

Goldman Sachs’ Alec Phillips said in a note he expects the tax reform process to begin in the House in late March or April.

Both Phillips and Cowen’s Krueger see potential for a tax overhaul to move rapidly through Congress. Krueger wrote that the July 28 start date for the congressional summer recess is the earliest date tax reform could be passed. Implementation wouldn’t be until Jan. 1, 2018.

Phillips’ prediction is for tax reform to become law by the third or fourth quarter of the year. He raises the possibility that Republican leaders could attempt to consider part of an overhaul — such as corporate reform — outside of the reconciliation process. Phillips wrote that he expects Republicans to initially seek Democrats’ support on tax reform. But ultimately, he predicted, the GOP would use the reconciliation process and pass reform without Democrats.