Congress gave final approval on Wednesday to President Biden’s sweeping, nearly $1.9 trillion stimulus package, as Democrats acted over unified Republican opposition to push through an emergency pandemic aid plan that carries out a vast expansion of the country’s social safety net.

By a vote of 220 to 211, the House sent the measure to Mr. Biden for his signature, cementing one of the largest injections of federal aid since the Great Depression. It would provide another round of direct payments for Americans, an extension of federal jobless benefits and billions of dollars to distribute coronavirus vaccines and provide relief for schools, states, tribal governments and small businesses struggling during the pandemic.

The bill is estimated to slash poverty by a third this year and potentially cut child poverty in half, with expansions of tax credits, food aid and rental and mortgage assistance.

While Republicans argued the plan, whose final cost was estimated at $1.856 trillion, was bloated and unaffordable, surveys indicate that it has widespread support among Americans, with 70 percent of Americans favoring it in a Pew Research Center poll released this week.

Mr. Biden and congressional Democrats planned an elaborate effort to promote it throughout the country, seeking to highlight an array of measures including tax credits for children and enhanced unemployment aid through Labor Day. The effort will begin on Thursday with a prime-time address by Mr. Biden, and congressional Democrats have already fanned out for scores of events in their states and districts to take credit for the legislation.

The campaign is intended to build support for provisions they hope to make permanent in the years to come, and to punish Republicans politically for failing to support it.