WASHINGTON — Senators from both parties remained doubtful about the administration’s ability to reunify more than 2,500 separated families, and skeptical that the “zero tolerance” policy will not be resurrected, following a closed-door briefing on Capitol Hill by administration officials.

Senators left the briefing frustrated at the lack of answers by a handful of administration officials, saying they were given no guarantee that every child separated from their parent would be reunited.

“There’s just the sheer lack of record keeping on the separated families and the inability to meet the most basic deadline,” Sen. Cory Booker, D-N.J., said.

Administration officials from the Justice Department, Customs and Border Protection, Immigration and Customs Enforcement, Citizenship and Immigration Service and Refugee Asylum International Operations met with members of the Senate Judiciary Committee on Tuesday after demands by senators and a blackout of information from the administration on the "zero tolerance" policy implemented by the Justice Department on a wide scale in early May.

“There was never the intention and certainly the design of any system to ever reunify these children from their parents,” Sen. Kamala Harris, D-Calif., said at a news conference. “So what we have seen over the ensuing weeks is complete pandemonium.”

The administration has been reluctant to answer any questions and have refused to appear at a public hearing.

Sen. Mazie Hirono, D-Hawaii, described a recent conference call between senators and Health and Human Services Secretary Alex Azar in which he seemed to be "patting his administration on the back on what a great job they were doing with this crisis that they created."

Hirono said that Azar sounded so robotic on the call that Sen. Catherine Cortez Masto, D-Nev., asked if Azar's speech to the senators was a recording.

Senators said Tuesday's briefing did show some progress in getting information compared to a smaller closed-door meeting at the Capitol with just a few senators several weeks ago.

“They didn’t have any answers for us then, so compared to that meeting this one had a lot more answers,” Sen. Chuck Grassley, R-Iowa, chair of the Judiciary Committee, said.

“They started giving the actual numbers,” Sen. Dick Durbin, D-Ill., said of today's meeting. “We have 180 parents who’ve been deported. We have 1,551 parents that are known to ICE. When we met three weeks ago they wouldn’t give us numbers. They just refused to even give an estimate of how many kids were involved here.”

Grassley told senators that ICE officials would appear before the committee for an open hearing on July 31, the first time an administration official would be on Capitol Hill to answer question in a public setting on the program.

But Hirono said ICE officials aren't adequate. She'd also like to hear from the DOJ and HHS in a public session.

The administration is up against a court-imposed deadline to reunite more than 2,500 children ages five to seventeen with their parents. Just over half — 57 — of the children under five who were taken from their parents have been reunited.

But some parents have been deported without their children, complicating efforts. Others won’t be reunified because it is thought the children were trafficked or abused.

“The answers that I’ve heard so far are patently unacceptable,” Booker said. “I do not see the means and the mechanisms with which they’re going to connect all these families.”

Three senators have introduced new comprehensive legislation to immediately reunify families. Sens. Harris, Cortez Masto and Jeff Merkley, D-Ore., introduced a bill that would also ensure that parents don’t have to pay to communicate with their children or for transportation to be reunified. It also prevents the deportation of parents until the family has been reconnected and prohibits any DNA testing from being used for immigration enforcement.

Harris called the proposal “a law that will exist permanently to ensure that never again will the United States government have the ability or the power to separate children from their parents in the way that has been done.”

Sens. Ted Cruz, R-Texas, and Dianne Feinstein, D-Calif, have been working on bipartisan legislation to prevent family separation for weeks, but a spokesperson said discussions are still ongoing.