Senate Appropriations Committee Chairman Richard Shelby, R-Ala., and Sen. Patrick Leahy, D-Vt., the top Democrat on the Appropriations Committee, have forged a tentative agreement on a $4.59 billion supplemental appropriations package for the border and humanitarian assistance, Fox News has learned.

The panel plans to hold a “markup” session Wednesday, a bipartisan effort to prepare the legislation for the floor and finalize the language of a bill that is intended to provide assistance to the Department of Health and Human Services' Office of Refugee Resettlement and the Department of Homeland Security in dealing with the surge of immigrants at the southern border.

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The proposed bill, at President Trump's request, was originally included as a part of the $19.1 billion supplemental aid package that was passed in May to provide disaster relief for hurricanes, wildfires, flooding and other weather-related issues that affected Puerto Rico, Georgia, Alabama, Florida, Iowa and Nebraska.

But Senate Democrats voted to separate out the nearly $5 billion humanitarian funding for the border from the package.

Senate Majority Leader Mitch McConnell, R-Ky., hopes to reintroduce the supplemental funding package focused mostly on providing $3.3 billion for necessities such as food, medical care and shelter for unaccompanied children and families coming across the border as a standalone proposal. The aim: Put the bill on the floor next week.

The majority of that funding, $2.9 billion, would be for ORR to deal with detained children who have yet to be placed into custody with a family member or sponsor in the U.S, while the remaining funds would allow DHS to set up and tend to immigrants in temporary processing facilities crossing the border as a family unit.

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The supplemental spending bill, if approved, will be an additional spending measure, on top of the 12 annual appropriations bills which run the government. Congress already approved a 13th appropriations bill when it OKd the disaster relief package earlier this spring, and a border humanitarian supplemental appropriations package would be the 14th spending bill for this fiscal year.