WASHINGTON — With fanfare and a White House kickoff, House Republicans unfurled a broad tax-overhaul plan Thursday that would touch virtually all Americans and the economy’s every corner, mingling sharply lower rates for corporations and reduced personal taxes for many with fewer deductions for home-buyers and families with steep medical bills.

The measure, which would be the most extensive rewrite of the nation’s tax code in three decades, is the product of a party that faces increasing pressure to produce a marquee legislative victory of some sort before next year’s elections. GOP leaders touted the plan as a sparkplug for the economy and a boon to the middle class and christened it the Tax Cuts and Jobs Act.

“We are working to give the American people a giant tax cut for Christmas,” President Donald Trump said in the Oval Office. The measure, he said, “will also be tax reform, and it will create jobs.”

It would also increase the national debt, a problem for some Republicans. And Democrats attacked the proposal as the GOP’s latest bonanza for the rich, with a phase-out of the inheritance tax and repeal of the alternative minimum tax on the highest earners — certain to help Trump and members of his family and Cabinet, among others.

And there was enough discontent among Republicans and business groups to leave the legislation’s fate uncertain in a journey through Congress that leaders hope will deposit a landmark bill on Trump’s desk by year’s end.