WASHINGTON (Reuters) -Democrats in the U.S. House of Representatives were poised on Friday to adopt the centerpiece of Democratic President Joe Biden’s domestic agenda: a $1.75 trillion social policy and climate-change bill and a $1 trillion bipartisan infrastructure bill.

The two pieces of legislation include the biggest upgrade of America’s roads, bridges and airports in a generation and the largest expansion of social programs since the 1960s.

After weeks of bickering between moderates and progressives, lawmakers were due to begin hours of debate on the “Build Back Better” social legislation here, which Democrats intend to pass through the narrowly divided House and Senate despite vehement opposition from Republicans.

The Democratic-controlled House was also expected to enact the Senate-passed infrastructure here bill and send it on to the White House for Biden’s signature.

An affirmative vote would bolster the credibility of Biden’s pledge to halve U.S. greenhouse gas emissions from 2005 levels by 2030 during the U.N. climate conference www.reuters.com/business/cop taking place in Glasgow, Scotland.

Biden, who left for Europe last week for the climate conference and a meeting of G20 leaders without a deal on the legislation, spent part of Thursday night calling various House members and urging them to approve the $1.75 trillion reconciliation bill, a White House official said.

Friday’s legislative momentum follows a disappointing loss for Democrats this week in Virginia, where a Republican won the governor’s office in a state Biden won handily in 2020.

The party is eager to show it can move forward on the president’s agenda and fend off Republicans in the 2022 midterm elections, when control of the House and Senate will be on the line.

The infrastructure bill, which passed the Senate here in August with 19 Republican votes, would fund a massive upgrade of America’s roads, bridges, airports, seaports and rail systems, while also expanding broadband internet service.

The “Build Back Better” package includes provisions on child care and preschool, eldercare, healthcare, prescription drug pricing and immigration.

Debate over that legislation quickly put on display a stark partisan contrast between Democrats and Republicans, who call the social-policy and climate-change agenda a “socialist” tax and spending bill.

“This is potentially a very black day for America,” said Republican Representative Glenn Grothman, who characterized the legislation’s child-care and preschool provisions as a “Marxist” effort to have the federal government raise children.

His comments were soon rebutted by Democratic Representative Sheila Jackson Lee, who said the bill would create a brighter future by supporting American families.

“Today is going to be a bright day in America, as Democrats govern and lead and make a difference,” Jackson Lee said.

The nonpartisan U.S. Joint Committee on Taxation issued a report scoring the “Build Back Better” legislation’s tax revenue provisions at $1.48 trillion over the next decade.

But top Democrats argued that the bill was fully paid for.

House Speaker Nancy Pelosi and Ways and Means Committee Chairman Richard Neal said the joint committee’s analysis did not account for additional revenue from provisions intended to enhance the Internal Revenue Service’s tax collection and to lower the cost of prescription drugs for the Medicare healthcare program for the elderly.