WASHINGTON — President Joe Biden was hosting two pivotal senators for meetings in Delaware on Sunday in hopes of resolving lingering disputes over Democrats’ long-stalled effort to craft an expansive social and environment measure.

Senate Majority Leader Chuck Schumer, D-N.Y., and Sen. Joe Manchin, D-W.Va., were scheduled to attend the session, the White House said.

Manchin and Sen. Kyrsten Sinema, D-Ariz., two of their party’s most moderate members, have insisted on reducing the size of the package and have pressed for other changes.

Democrats initially planned that the measure would contain $3.5 trillion worth of spending and tax initiatives over 10 years. But demands by moderates led by Manchin and Sinema to contain costs mean its final price tag could well be less than $2 trillion.

Disputes remain over whether some priorities must be cut or excluded. These include plans to expand Medicare coverage, child care assistance and helping lower-income college students. Manchin, whose state has a major coal industry, has opposed proposals to penalize utilities that do not switch quickly to clean energy.

The White House and congressional leaders have tried to push monthslong negotiations toward a conclusion by the end of October. Democrats’ aim is to produce an outline by then that would spell out the overall size of the measure and describe policy goals that leaders as well as progressives and moderates would endorse.

The wide-ranging measure carries many of Biden’s top domestic priorities. Party leaders want to end internal battles, avert the risk that the effort could fail and focus voters’ attention on the plan’s popular programs for helping families with child care, health costs and other issues.

Democrats also want Biden to be able to cite accomplishments when he attends a global summit in Scotland on climate change in early November. They also have wanted to make progress that could help Democrat Terry McAuliffe win a neck-and-neck Nov. 2 gubernatorial election in Virginia.

The hope is that an agreement between the party’s two factions would create enough trust to let Democrats finally push through the House a separate $1 trillion package of highway and broadband projects.

That bipartisan measure was approved over the summer by the Senate. But progressives have held it up in the House as leverage to prompt moderates to back the bigger, broader package of health care, education and environment initiatives.