Agencies and federal officials at the southwestern border say they desperately need emergency humanitarian aid to help manage the flow of migrants. Both the Senate and the House have put forward versions of legislation that would allocate about $4.6 billion to the border, and both chambers are expected to vote as early as Tuesday.

But it remains unclear how those bills will be reconciled. Here are the differences in how the House and Senate have proposed allocating the money, based on summaries provided by the chambers’ appropriations committees.

Under pressure, House leaders attached more policy strings.

In an amendment released early Tuesday, Democrats plan to add language that would require Customs and Border Protection to establish plans and protocols to deliver medical care at border shelters, improve nutrition and hygiene, and train personnel to ensure the health and safety of children and adults in custody.

Another new provision would require the secretary of health and human services to specify which requirements are being temporarily waived to deal with any sudden influx of migrants. That amendment would limit the detention-center stay of any unaccompanied child to 90 days unless written notification is submitted to Congress attesting that no other facilities are available.