The House approved a budget outline Thursday that opens the door for President Trump and Republican leaders to pass the tax code overhaul they released last month, but that is only a first step in a long and uncertain path for Trump's vision of sweeping tax cuts.

Republicans have outlined an ambitious plan to collapse brackets, change rates, eliminate deductions and revamp how big and small businesses are taxed.

"We want the American people to wake up in the new year with a new system," House Speaker Paul Ryan, R-Wis., said.

But for that to happen, Trump and Congress will have to move with agility and political coordination that they could not muster on other priorities this year, especially overhauling health insurance. And it will have to happen while other issues also compete for time on the agenda, including some Congress postponed from September into December.

Here's a look at what must occur for a bill to reach Trump's desk, and what could get in the way.

First step: Pass a budget

Republican leaders say they would welcome bipartisan involvement, but they have decided to use a procedure called reconciliation to prevent Democrats from blocking a tax bill through a filibuster in the Senate. Overcoming a filibuster requires 60 votes; Republicans hold 52 Senate seats. Under reconciliation, a bill can pass with only 50 votes, with the vice president breaking the tie.

To use reconciliation, the House and Senate both must pass a budget resolution for 2018 that spells out the impact tax changes will have on federal revenues. Once they do that, a bill that meets those conditions would be filibuster-proof.

The House passed its budget, which says tax cuts should be offset by other changes to the tax code and cuts in spending, on Thursday.

The Senate Budget Committee approved a different measure Thursday afternoon that says tax breaks could cost as much as $1.5 trillion over 10 years. The Senate is out of session next week, and if the budget resolution is the first item taken up when it returns, passage on the floor will take time because the rules allow senators to offer multiple amendments to change provisions.

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These amendments often do not have the force of law, but both parties tend to demand votes designed to get senators facing re-election to cast difficult votes that can be used in campaign ads.

Liberal groups trying to derail the tax package have set their sights on defeating the budget. One tactic is to focus on the resolution's call for $5.1 trillion in spending cuts over the coming decade, arguing that cuts that deep would affect popular programs such as Medicare.

Some conservatives have also sounded the alarm about potential expansion of the national debt, challenging the arguments by supporters of the tax overhaul who believe economic growth produced by tax changes will offset reduced revenues. The House budget vote Thursday included 18 Republicans voting "no" — because of concerns over deficits or parts of the tax package that could hurt their states — which highlights some of the hazards GOP leaders may face as the tax plan moves forward.

Once the Senate passes a budget, a conference committee would then have to work out differences with the House version. Then each chamber would have to vote again on the conference agreement. That all could be done by Halloween, but only if the plan doesn't hit any speed bumps.

Release a bill

Though months of meetings behind closed doors preceded the tax plan's release, it lacked vital details, such as the income levels for the new individual tax brackets and how the plan to shift corporate taxes from a global system to a domestic one would work.

Filling in those blanks requires legislation, which the Constitution says must originate in the House. The chairman of the House Ways and Means Committee, Rep. Kevin Brady, R-Texas, said that once the budget resolution "provides our runway to land bold tax reform on," his committee will unveil a bill.

To get around budget rules designed to prevent increasing the deficit, for example, some tax cuts may be crafted to be temporary, so that the money that would come in when they expire would offset the upfront revenue loss of cutting the taxes in the first place. This would count even if lawmakers have no intention of actually letting the tax breaks expire.

Once a bill is unveiled, which probably would not be before next month, it will be up to Ryan and Brady how quickly it will be considered and passed by committee.

During that process, members could offer amendments that would affect whether the bill gains or loses support on the floor.

Pass the House

After the bill gets out of the Ways and Means Committee, the full House will be able to weigh in. Ryan could restrict whether members could offer floor amendments, but if a bloc of representatives seeking changes is large enough to endanger passage, he could open the bill up to changes.

To date, supporters of a tax overhaul have been trying to build momentum for the bill by arguing it will be a boon to middle-class families. They have brushed aside criticisms from Democrats and some independent analysts about the possible cost of the plan, saying details still are being decided so any bottom-line analysis is premature.

But an actual bill will show who the winners and losers are. And advocates for the losers, including lobbyists for corporations that might have to pay higher taxes and lawmakers representing states or districts that rely heavily on deductions slated for deletion, will be demanding to know why they should be forced to pay more.

"If you start with the idea that everybody's a winner, it makes creating losers hard," said Marc Goldwein of the Committee for a Responsible Federal Budget.

How quickly Ryan brings the bill to the floor will depend on how soon he and his leadership team are confident they have the votes for passage.

Repeat in the Senate, with a twist

If the bill passes the House, however, it is almost certain, based on past interactions between the two chambers, that the Senate would want to make its own changes to the bill.

For the Senate to simply take up and pass the House bill, there would have to be a party-line effort to reject changes both in committee and on the floor.

The chairman of the Senate Finance Committee, Republican Orrin Hatch of Utah, assured the committee's top Democrat, Ron Wyden of Oregon, on Tuesday that there would be a full committee process where members could offer amendments.

Senate rules also give the entire chamber the opportunity to offer amendments when the bill gets to the floor.

"Everybody gets a vote on their amendments, and they're going to enjoy making the Senate vote on some politically painful amendments," said Mac Campbell, a former deputy staff director and general counsel of the Senate Finance Committee. "That's just going to be ugly."

Majority Leader Mitch McConnell, R-Ky., would have to impose strict party discipline to prevent the Senate from passing a change that might endanger the chances of the revised bill passing the House.

If the bill survives the Senate, it would have to go back to the House, where Ryan would decide whether to just call a vote on the Senate version or send it to a conference committee to work out the differences.

Competition from other issues

All of this legislative maneuvering will be going on while Congress is grappling with a raft of other major issues.

By early December, Congress has to decide how to fund the government for 2018 and whether to again raising the debt limit; billions of dollars of disaster relief spending will have to be approved; and Trump has set a March deadline for Congress to pass a bill dealing with undocumented immigrants brought to the country as children

"For reform to happen you need momentum, you need less distractions with other policies and issues," said Todd Simmens, a former counsel to the Joint Committee on Taxation now with the accounting firm BDO. "Right now, there are other things going on outside of taxes, and we are losing legislative days as we go."

The time frame to pass a tax bill under reconciliation would run until the end of next September. But failing to get a tax bill passed this year increases the chance that the process gets bogged down by the midterm elections next year.