The Democratic co-sponsor of White House-backed prison reform legislation is threatening to walk away from the effort after legislative attempts to attach a concealed carry expansion to the bill, multiple sources familiar with the draft legislation tell ABC News.

“We will walk away [and] have no problem doing so," a source close to House Judiciary Democrats' strategy said. "We're saying put up or shut up. Prove you're serious."

The Prison Reform and Redemption Act, which Democrat Rep. Hakeem Jeffries' is co-sponsoring along with Republican Rep. Doug Collins, has the support of the White House in an effort that has been led by the president's son-in-law and senior adviser Jared Kushner.

But an apparent attempt to tack on an expansion of concealed carry to the bill now has Jeffries reconsidering his position. The draft language is not public and ABC News has not reviewed updates to the bill.

“They’re full of it," a person close to Jeffries said in reference to House Republicans. "We will only support a bill that ensures that currently incarcerated individuals are job ready upon release and respect and protects the dignity of women. This bill fails to meet that standard and is loaded with poison pills. In the aftermath of the Florida school shooting when a country is moving toward gun safety, they try to expand concealed carry, which is a nonstarter."

"This bill fails to meet that standard and is loaded with poison pills. In the aftermath of the Florida school shooting when a country is moving toward gun safety, they try to expand concealed carry, which is a nonstarter," the source said.

Kushner was on Capitol Hill Wednesday morning for a meeting on the legislation and had expected to meet with Jeffries along with House Speaker Paul Ryan and Rep. Collins, among members of the Problem Solvers Caucus, according to a list of expected participants provided by the White House.

Jeffries, however, did not attend the meeting. His office declined to comment on his absence.

But a White House official said that Kushner and Jeffries now plan to have a call on Thursday to go over the language of the legislation. The official also would not elaborate on Jeffries' absence from the meeting earlier in the day.

The White House also did not elaborate on the addition of the concealed carry element to the legislation and did not take a position on the change.

Mark Holden, who leads a Koch brothers-backed prison reform group and has worked in close partnership with Kushner's team on the issue, says he hasn't heard from anyone who favors the change either at the White House or among conservative groups collaborating on the issue.

"We’ve been talking for months about a clean prison reform, this is not a clean reform bill," Holden said.

Democratic prison reform advocate Van Jones was at the meeting with Kushner this morning. While his group #Cut50 remains engaged in the process, Jones has described the concealed carry addition to the legislation as being "bird poop in the cool aid" and of serious concern.

"We believe strongly that we should be at the table helping negotiate, but there are some things need to be changed," #cut 50 co-founder Jessica Jackson Sloan said.

Jeffries continues to view Kushner, as well as his Republican co-sponsor Rep. Collins, as serious partners in the legislative effort to address prison reform, a person familiar with the effort said and added that the reason for the current impasse appears to be other Congressional Republicans who have since gotten involved in the effort.

Rep. Jeffries' office declined to comment for this story.

The Collins-Jeffries bill had been on track to be considered at the committee level in the House this month.