Congressional leaders reach funding agreement -- but could a shutdown still happen?

Congressional leaders and the White House have reached agreement on how to fund the Department of Homeland Security, one of the last hurdles to prevent an approaching partial government shutdown deadline Friday -- but it might not come together in time.

Funding for DHS was the final major sticking point in negotiations for the six spending bills that need to pass to avert a shutdown. The details of the negotiation haven't yet been released.

The agreement on DHS funding paves the way for lawmakers to start processing the spending package in the hopes of meeting Friday's deadline to avert a partial government shutdown. A deal has been reached on the remaining six government funding bills, congressional leaders confirmed.

"An agreement has been reached for DHS appropriations, which will allow completion of the FY24 appropriations process," said Speaker Mike Johnson. "House and Senate committees have begun drafting bill text to be prepared for release and consideration by the full House and Senate as soon as possible."

But with negotiators still working out the details and legislative text of the full agreement still not out, lawmakers are up against the clock to prevent a shutdown. The House has a rule requiring 72 hours for members to review legislation before voting; the Senate also can take a few days to process House-passed bills. That means a vote may not happen until the end of the week or weekend -- increasing the chances of shutdown -- unless Johnson speeds up the process.

Another wrinkle: the funding agreement may face pushback from some House GOP hard-liners. The House Freedom Caucus -- made up of many of the House's most conservative members -- have urged members of the party to reject the appropriations package "otherwise Republicans will be actively funding Biden's 'open borders' policies" -- a reference to the DHS deal, its members said in a letter Monday.

On the Senate floor Tuesday, Senate leaders expressed optimism that the government funding deal could avert the partial government shutdown, but said it's going to take a whole lot of cooperation to prevent at least a brief lapse.

Majority Leader Chuck Schumer called it "good news" that the agreement had been reached.

"It is a very good sign that we begin the week by announcing this agreement. But I want to be clear -- there is a lot of work to do in the coming days," Schumer said. "If both parties proceed in the same manner we did two weeks ago -- quickly, constructively and without unnecessary partisan dithering -- then I am hopeful that we can finish the appropriations process without causing a lapse in government services."

"We haven't had a government shutdown since 2019 there is no good reason for us to have one this week now that we are getting very close to finishing the job," he continued.

In separate remarks, Minority Leader Mitch McConnell thanked his appropriators for their work on the package, but similarly warned of the cooperation necessary to get things finished.

"This week, the Senate faces one more test to complete its annual appropriations process and the stakes really couldn't be higher for American security at home and abroad," McConnell said.

President Joe Biden said Tuesday that once Congress approves the package, he "will sign it immediately."

This shutdown threat has been the latest in a series of challenges for Johnson, whose party maintains a razor-thin margin in the lower chamber.

Congress has nearly shut the government down, at least partially, five times since October. During those votes, Johnson has had to rely on House Democrats' votes to prevent shutdowns -- something that landed his predecessor Kevin McCarthy in hot water with the party and contributed to his ouster last year.

ABC News' Sarah Beth Hensley contributed to this report.