Health insurer CareFirst, part of the Blue Cross Blue Shield group, left the top insurance lobby America's Health Insurance Plans at the end of 2017, according to multiple reports.
AHIP said Friday evening the exit was a "business decision."
CareFirst is the fourth major departure from AHIP and the second this week after Humana announced its exit. Other major insurers that have left AHIP include UnitedHealth Group and Aetna.
However, the lobbying group noted that it has added 12 members this year.
"We still have the most health plans as members, and we remain their advocate in Washington and the states," AHIP said.
The departure of CareFirst comes after AHIP had disagreements with Congress over various bills to repeal and replace Obamacare. The group also did not convince the Trump administration to restart payments to insurers known as cost-sharing reduction subsidies.