A fight over immigration enforcement language has emerged as an 11th-hour roadblock to getting a disaster aid deal before lawmakers leave Washington for the Memorial Day recess.

The sticking point, according to lawmakers and aides, is how much of the administration's $4.5 billion request for emergency funding for the U.S.-Mexico border will be included in the disaster aid package. ADVERTISEMENT The White House's $4.5 billion request included $3.3 billion for humanitarian assistance, which the administration said would be used to increase shelters and care for unaccompanied minors, in addition to processing arrivals. About $1.1 billion would go toward other border operations, such as expanding the number of detention beds and providing more investigation resources. Democrats have agreed to include humanitarian aid as part of an agreement on the disaster package, but a previous offer didn't include the administration's request for more money for Immigration and Customs Enforcement (ICE) detention beds, considered a non-starter for most of the caucus. Senate Appropriations Committee Chairman Richard Shelby Richard Craig ShelbySenate GOP eyes early exit Dems discussing government funding bill into February GOP short of votes on Trump's controversial Fed pick MORE Senate Appropriations Committee Chairman(R-Ala.) said Wednesday evening that the negotiations still had "several" issues to resolve.

"I'm hoping they're not insurmountable," Shelby told reporters. "I think right at the moment it's in abeyance. It's not there yet."

Shelby told reporters Wednesday morning that the debate was stuck on funding for ICE and detention beds for migrants detained along the U.S.-Mexico border.

"We're just waiting on the Republicans in the House. We worked everything to here," Leahy said. "They've got some immigration and other things."

Asked about the status of talks, a House Democratic aide said that they were "working in good faith with our House Republican counterparts to conclude the final issues related to the border supplemental."

Shelby, Leahy and other top lawmakers were initially expected to meet on Wednesday evening to try to hash out the remaining roadblocks. Shelby told reporters the meeting had been called off because of scheduling conflicts but that they were trying to reschedule for later Wednesday.