"We review our memberships on an annual basis and this year have decided to discontinue our membership in ALEC," Exxon spokesman Scott Silvestri said.

ALEC, a coalition of state lawmakers and companies that proposes legislation, has been criticized for its stance on climate change, tort reform and gun control. In recent years, it has lost dozens of members, including BP, Royal Dutch Shell Group, Ford Motor, and Expedia Group.

The group said in a statement that member "government relations strategies change over time," and lauded Exxon for its past work with the group on science, technology, engineering and math education issues.

Exxon's decision not to renew its membership followed a split with the lobby group last year over the Environmental Protection Agency's regulation of greenhouse gas emissions.

Ben Ratner, a senior director at the Environmental Defense Fund, a non-profit group focused on environmental issues, called Exxon's departure "an important statement," noting the oil company recently joined BP, Shell and others supporting steps to reduce natural gas emissions from their operations.