WASHINGTON — Lawmakers involved in budget negotiations reached a deal Saturday that takes a major step toward fully funding the government through the end of September, agreeing to budget levels for a wide range of government programs.

The House and Senate committees that negotiated the deal declined to release details on the agreement, and one of the most crucial issues appears to remain unresolved.

In setting the new pact, congressional leaders reached an agreement on spending levels for the Department of Homeland Security, but they did not agree on how much of that money should be diverted toward constructing a wall along the Mexico border. President Trump has demanded $5 billion for that project, a level Democrats have long refused to meet.

The agreement, though, does set spending levels for the 12 annual must-pass appropriations bills that fund everything from the Pentagon to the Department of Health and Human Services. Because such a deal had remained elusive, lawmakers passed a bill in recent days that temporarily extended these programs through Dec. 20, giving them more time to negotiate.

Negotiations focused on overall spending levels for agencies – not specific projects, and those details will still need to be worked out in December by congressional appropriators. That’s why no specific figure was reached for Trump’s border wall, which as in the past has been an obstacle to compromise. Instead negotiators settled on a top line budget number for DHS. Congressional appropriators will still need to negotiate how the DHS money is allocated before it can be voted on by Congress next month.

Due to Democratic opposition to the wall, the DHS spending bill is unlikely to provide for the full $5 billion Trump has sought for wall construction.

The administration has made clear that if it doesn’t get all the wall money it wants from Congress it will use executive authority to take money from other accounts.

That’s a step the administration took earlier this year after a 35-day government shutdown ended without Congress giving the White House all the wall money he sought.

The new deal, if it holds, would provide for passage of all 12 annual spending bills by Dec. 20, according to Democratic and Republican aides in the House and Senate. The aides spoke on condition of anonymity because they weren’t authorized to disclose details of the new agreement. The breakthrough came after months of on-again off-again talks.

The federal government spends more than $4 trillion on various programs, including Social Security, Medicare, Medicaid, and other social welfare programs. But more than $1 trillion of the budget must be authorized each year by Congress or those programs risk shutting down. That’s the process lawmakers are now trying to complete.

Overall, the deal provides for an increase of $22 billion for defense spending and $27 billion for non-defense programs for 2020 – compared to the existing 2019 budget levels. Those numbers had been previously agreed to.

Details must still be hammered out on specific programs, including the wall. And, if finalized, the bills would have to pass both chambers of Congress – and be signed by Trump. The votes would likely come around the same time that the House of Representatives, controlled by Democrats, is voting on articles of impeachment against Trump.

Even with the agreement in place, it’s far from certain that Congress will be able to pass the needed legislation in time. And disagreement on the wall or other issues could cause the process to stall once again or even collapse.

The White House Office of Management and Budget declined to comment on the new deal.