The exacting pace is meant to maximize party cohesion and neutralize attacks by Democrats and business groups. If Republicans stick to it, they will speed what could be a 1,000-page piece of legislation, affecting every corner of the United States economy, through the House and the Senate in less than three weeks.

Democrats were swift to criticize the approach, saying it was an attempt to hide tax changes that will hurt, not help, middle-class families. Senator Ron Wyden of Oregon, the top Democrat on the Senate Finance Committee, said the bill was shaping up to be “a bunch of false promises to the middle class.” Republicans, he said, “know the details — the specifics of what they’re really about — will be hard to argue in the sunlight.”

Lawmakers and committee staff members must still resolve some of the thorniest issues before they can release a bill, including where to draw income lines for tax brackets, how high to set the top personal income tax rate and how to ensure that major changes to the way that multinational corporations are taxed do not encourage them to shift more money overseas. The biggest question is how to offset enough tax revenue that will be lost from cutting rates to remain within the rules of the Senate budget reconciliation process, which allows Republicans to bypass a Democratic filibuster.

The budget measure approved on Thursday would allow for a tax bill that adds as much as $1.5 trillion to federal deficits over a decade, at a time when the federal government’s debt has already topped $20 trillion. The deficit for the 2017 fiscal year, which ended Sept. 30, totaled $666 billion, an increase of $80 billion from the previous year.

The outline of the tax plan unveiled in September would cut the corporate income tax rate to 20 percent, from 35 percent; collapse individual income tax brackets from seven to three or four, with tax rates of 12 percent, 25 percent and 35 percent, and possibly one higher; and nearly double the standard deduction, to $12,000 for individuals and to $24,000 for married couples filing jointly.