WASHINGTON — Senate Republicans outlined their vision on Thursday for overhauling the tax code, proposing a one-year delay in President Trump’s top priority of cutting the corporate tax rate while reinstating some prized tax breaks used by middle-class families.

The Senate bill differs significantly from the House version approved by the Ways and Means committee on Thursday: It would preserve some popular tax breaks, including ones for mortgage interest and medical expenses, and would maintain a bottom tax rate of 10 percent for lower earners. But it would also jettison the state and local tax deduction entirely and delay the enforcement of a 20 percent corporate tax rate until 2019, which could rankle the White House and mute the economic growth projections that Republicans are counting on to blunt the cost of the tax cuts.

The disparate bills show the competing pressures that Republican lawmakers are facing and the calculations that Senate and House leaders are making to ensure passage of the bills through their respective chambers. While both bills share the main priorities of cutting corporate and individual taxes, they diverge on matters of high political sensitivity, particularly for vulnerable House Republicans from high-tax states and for Senate Republicans concerned about adding to the federal budget deficit.

Senate staff members said their draft would require changes, likely major ones, to survive procedural rules that allow it to pass on a party-line vote. Those changes could include setting some of the tax cuts to expire after a period of years.