Washington — Republicans set an aggressive timeline for passing legislation to overhaul the nation’s tax code, putting pressure on senior lawmakers and the White House to resolve major disagreements about the effort before a Wednesday deadline to introduce a bill.

In a sign of the challenge to come, House Republicans narrowly passed a budget measure on Thursday allowing the tax overhaul to increase the deficit by $1.5 trillion over a decade. The effort succeeded with support from only two lawmakers to spare, as a group of northeastern Republicans opposed the budget resolution because of concerns that the tax rewrite could hurt their constituents.

The Wednesday deadline sets up what is likely to be several days of intense lobbying to shape the bill.

The House and Senate aim to pass legislation by Thanksgiving, with the goal of finalizing the bill and sending it to President Donald Trump by year’s end.

“It shows the strength of the willingness to get tax reform done,” House Majority Leader Kevin McCarthy, R-Calif., said of the 216-to-212 budget vote.

But as they rush forward, lawmakers have not resolved basic questions about how the tax overhaul would affect the wealthy, the middle class or lower-income earners.

Still unresolved were several questions: whether the legislation would moderate the expected benefits for the wealthy; whether it would cap or eliminate popular middle-class tax breaks like the state and local tax deduction or the tax benefit of 401(k) retirement plans; and how dramatically it would expand a child-care tax credit that helps working-class families. Also on the table were several critical questions about how the corporate tax code would change.

Lawmakers planned to spend the coming days trying to resolve those concerns, with hopes that they would avoid the kind of interparty squabbles that have doomed other major legislative efforts this year.

They also hoped to avoid unexpected criticism from Trump, who has railed against GOP hopes of overhauling the 401(k) provision.

Asked Friday if he was concerned that Trump might undermine the effort, House Speaker Paul Ryan, R-Wis., said — half jokingly — that his party’s leader would be beginning a lengthy trip to Asia next week.

“He’s going to be in Asia, number one,” Ryan said. “No, I’m just kidding. That was kind of a joke. I was sort of joking on that one.”

Ryan went on to say that he was working closely with the White House on the bill, but several senior administration officials said they had not seen a final draft of what the tax plan would look like.