In a letter to Democrats on Saturday the House speaker, Nancy Pelosi, set her sights high, saying Joe Biden’s $3.5tn spending package, a bipartisan infrastructure deal worth $1tn and a measure to expand government funding “must pass” next week.

During an unusual Saturday session at the Capitol in Washington, Democrats pushed the $3.5tn, 10-year spending bill through the House budget committee.

Biden, Pelosi and the Senate majority leader, Chuck Schumer, must resolve differences among Democrats over the package’s final price tag, which seems sure to shrink.

Before the measure the budget committee considered on Saturday even reaches the House floor it is expected to be changed to reflect whatever accords are reached.

“The next few days will be a time of intensity,” Pelosi wrote to Democrats on Saturday, adding that the spending plan, the Build Back Better Act, would “make sure the wealthiest and corporations pay their fair share”.

“This bill is a disaster for working-class families,” said Jason Smith of Missouri, the top Republican on the budget committee.

To nail down moderate support for an earlier budget blueprint, Pelosi promised to begin consideration of the $1tn infrastructure package by Monday 27 September.

Many moderates who consider the infrastructure bill their top goal want to cut the $3.5tn spending package and trim or reshape some programs.

Democrats can lose no votes in the Senate and a maximum of three in the House.