House Democrats took their first steps toward expanding Medicare and authorizing 12 weeks of paid family and medical leave for most Americans, even as some of the party’s lawmakers raised fresh criticisms about the speed and scope of the party’s broader spending aspirations.

The series of votes in front of the tax-focused House Ways and Means Committee marked a critical, early milestone as lawmakers continue to craft a broader bill encapsulating President Biden’s economic policy priorities — a grueling process that is set to resume across the Capitol next week.

The paid family leave plan could pave the way for most workers to collect at least two-thirds of their earnings if they are absent for reasons including childbirth or illness, with additional sums set aside for lower-income families. The Medicare expansion, meanwhile, could soon open the door for seniors to obtain new dental, vision and hearing coverage.

The provisions make up a central component of a still-forming $3.5 trillion economic package that Democrats hope can deliver sweeping overhauls to federal health care, education, immigration and tax laws. Lawmakers on the House’s top tax committee adopted the policy Thursday, along with an additional proposal that helps Americans save for retirement — two elements in a sprawling agenda they are set to tackle further in the days ahead.

“Our nation’s inadequate child care options and lack of paid family and medical leave have prevented talented workers from contributing to our economy,” said Rep. Richard E. Neal (D-Mass.), the chairman of the Ways and Means Committee, to open the debate.

The vote came as part of several days of marathon legislative sessions across the House, as Democrats raced to try to finalize their tax-and-spending measure before the end of September. But it was not without its flare-ups, as moderate and liberal-leaning Democratic lawmakers continued to squabble over the size of their economic package and the speed at which they hope to pass it.

In a sign of lingering, intraparty tensions, Rep. Stephanie Murphy (D-Fla.) cast a symbolic vote against the paid-leave program and other proposals that came before the Ways and Means Committee. Even though she said she supports Democrats’ broader spending efforts, she faulted the party for failing to explain how much the committee’s efforts would cost — and how lawmakers plan to pay for them.

A leader of one of Democrats’ moderate-leaning caucuses, Murphy further laid into Democrats for racing ahead to try to adopt as much as $3.5 trillion in spending before the end of September, a deadline she describe as “artificial.” And the congresswoman teased potential concerns about its policy scope, saying she did not think “we can afford to do everything.”

Murphy’s objections did not threaten the panel’s immediate work on paid leave and other issues. But her concerns still could foreshadow additional trouble to come at a time when Democrats are facing growing resistance from among their own ranks — and are far from finished in their work.

These votes marked only the beginning of a long journey for Democratic lawmakers, whose $3.5 trillion package would amount to the largest such tax-and-spending measure in U.S. history. A dozen committees are scheduled to hold their own gatherings in the coming days as part of a push by House Speaker Nancy Pelosi (D-Calif.) to conclude its initial legislative legwork by Sept. 15.

As the House’s top tax panel met, another group of lawmakers focused on education approved more than half a trillion dollars in its own investments — including a $450 billion plan to improve child care and offer prekindergarten to all children ages three and four. Rep. Robert C. “Bobby” Scott (D-Va.), the committee’s chairman, said the spending would “transform our economy in ways that will make our nation more prosperous, equitable and fairer.”

House Democrats also unfurled plans to spend roughly $320 billion to improve public housing and help low-income Americans stay in their homes, a series of legislative proposals lawmakers led by Rep. Maxine Waters (D-Calif.) are set to consider next week. So too did work continue on Democrats’ plans to try to lower prescription drug costs for consumers, invest anew in the country’s program to prepare for future pandemics and help millions of low-income Americans obtain access to Medicaid.

Much of the debate over health policy is slated for consideration next week, when the House Energy and Commerce Committee also hopes to consider billions in additional spending to combat the threat of climate change — including a new program to pay electricity suppliers for reducing emissions while penalizing those who do not. The panel has also proposed spending $1 billion to empower federal regulators to probe tech giants including Apple, Facebook and Google.

In bringing these proposals to early votes, Democrats have anticipated growing dissent within their own caucus. Moderate-leaning lawmakers including Sens. Joe Manchin III (D-W.Va.) and Kyrsten Sinema (D-Ariz.) in recent weeks have sounded early concerns with the package and its potential $3.5 trillion price tag, raising the possibility that Democrats may have to scale back some of their ambitions to proceed.

But the looming threat did not seem to deter party lawmakers in the House as they muscled ahead with some of their ambitious spending plans anyway.

For the House Ways and Means Committee, a key focus was paid family leave, a priority for Democrats made more urgent amid the coronavirus pandemic. Even in the face of a public health crisis, lawmakers said Americans still could not easily take off from work without putting their jobs, paychecks and families at risk.

The proposal the panel adopted aims to remedy the gaps by commissioning a new federal system to be set up by 2023. Employers who already possess paid leave programs could keep them if they meet minimum federal standards, as could states that offer their own, comparable benefits. Lawmakers previously approved paid leave in earlier pandemic aid packages, but some of the more robust aid has expired — leaving only a voluntary system currently in place.

“For the majority of American workers, there’s no paid leave at all,” said Kathleen Romig, a senior policy analyst at the Center on Budget and Policy Priorities. She noted that not even every U.S. worker currently can obtain unpaid family medical leave, either. “It’s a big problem that became urgent in people’s minds during the coronavirus pandemic.”

The panel of Democratic lawmakers also advanced a proposal that they say would help Americans save for retirement, including by requiring employers to enroll workers in 401(k)-type plans if the company does not sponsor a plan of its own. And it adopted a major expansion of Medicare that would allow seniors to obtain dental, hearing and vision benefits, an idea with broad support among Democratic lawmakers. But some in the party have taken issue with the legislation from Neal, which delays dental benefits until 2028, setting up a clash as debate continues.

The discussion set the stage for the panel to turn next week to an even fiercer fight — figuring out how to pay for as much as $3.5 trillion in new spending. Democrats have eyed tax increases on corporations, wealthy families and investors, but significant divisions among the party’s factions threaten to jeopardize their commitment to pay for the package in full.