President Joe Biden aims to turn his win on sweeping infrastructure reform into success on his social welfare and climate agenda Thursday as lawmakers begin debate on his giant Build Back Better proposals.

The House cleared the $1.2 trillion bipartisan infrastructure bill -- America's biggest public-works package since Dwight Eisenhower created the interstate highway system in 1956 -- earlier this month.

Democrats in the lower chamber are on track to follow that by passing the party-line $1.75 trillion "human infrastructure" package as early as Thursday night but face headwinds amid rising gas and food prices.

"Build Back Better is a spectacular vision for the future, with transformational and historic action on health care, family care and climate that will make a significant difference in the lives of millions of Americans," House Speaker Nancy Pelosi said in a letter to her members.

"It will create millions of good-paying jobs, lower families' costs and cut their taxes, while making the wealthiest few and big corporations pay their fair share."

But concerns over spiraling living costs have cast a shadow over the president's victory lap as he tours America touting his giant roads and bridges upgrade.

Annual inflation jumped to 6.2 percent last month, giving Republicans another cudgel to bash Biden with as they bid to retake both chambers of Congress in next year's midterm elections.

Only 41 percent of respondents to a new ABC News-Washington Post poll said they approve of Biden's work in office, compared to 53 percent who disapprove.

House Democrats, who cannot afford to lose more than three members to win any party-line vote, are projecting optimism that they can overcome persistent infighting that has dogged debate over Build Back Better for months.

A handful of centrist Democrats wanted a full analysis from the Congressional Budget Office to clarify the price tag of the package before they'd agree to vote.

Pump the brakes

The CBO is expecting to complete that work on Friday, with a vote most likely coming that night or the following day -- although some Democrats are pushing colleagues to move to a vote as early as Thursday.

Even if the House passes the bill this week, there's still a rocky road ahead as it faces rewrites in the Senate, and may not even be considered by the upper chamber until December or possibly even January.

The Senate has been locked in a 50-50 split for one of the longest periods in its history and, with no votes to spare, every Democrat effectively has a veto on any bill as long as Republicans stick together.

Progressives in both chambers are pushing for a national paid family leave program and a bigger expansion of health care benefits, but the latest inflation data could harm those efforts.

West Virginia's Senator Joe Manchin, the biggest Democratic obstacle to getting the legislation to Biden's desk, has indicated he is opposed to family leave, one of the most popular planks of the package.

He has argued in any case that the Democrats should pump the brakes on spending until inflation is brought under control.

Tensions between moderates and progressives in the House have eased as they look to clear the bill -- but it remains unclear whether either side will vote for the version that comes back from the Senate.

The White House has tried to frame the president's agenda as a long-term answer to rocketing prices, highlighting statements this week from leading ratings agencies that it would not worsen the problem.

"Our Build Back Better Act will help lift long-term economic growth through stronger productivity and labor force growth -- and not add inflationary pressures to the economy," Vice President Kamala Harris said in a statement.

Many economists agree, but say the problem could still get worse next year before relief comes.