A Senate working group tasked with drafting legislation to repeal Obamacare is opening its doors to anyone in the Republican conference.

Sen. Bill Cassidy, R-La., told reporters Thursday that he heard everyone is invited to attend the twice-weekly working group meetings. Cassidy, who has been spearheading bipartisan talks alongside Sen. Susan Collins, R-Maine, joined the closed-door meeting Thursday, which focused on tax credits to reduce healthcare costs.

The selection of the original members of the working group ignited immediate criticism as no female senators were asked to join.

GOP leadership responded that women members of the conference will have input on the healthcare reform, pointing to thrice-weekly lunches to update members on healthcare legislation.

Sen. Orrin Hatch said about 15 to 20 senators attended Thursday's meeting. The working group normally has 14 members, but other members have shown up periodically over the past few weeks.

Cassidy has been doing work on healthcare reform parallel to the working group meetings. He and Collins spearheaded a small bipartisan gathering that included three Democrats on Monday.

Other working groups have held meetings as well.

Collins said she attended a working group helmed by Sen. Rob Portman, R-Ohio, on Medicaid. Portman and Sen. Pat Toomey of Pennsylvania have been tasked with working together to come up with a compromise on on Medicaid growth rates.

It is not clear when any legislative text will emerge from any of the groups. Senators are ironing out major differences on everything from Medicaid spending to whether to keep Obamacare's individual mandate for a few years.

Sen. John Hoeven, R-N.D., told the Washington Examiner that the group is trying to get consensus and "that takes a lot of work."

He said that the group is anticipating a score from the Congressional Budget Office on the House bill approved this month, expected next week. An earlier score made before major changes found that 24 million people could go without insurance over the next decade.

"We are talking about at least another month before you are starting to have something where hopefully there is consensus and you have a score on it," he said.