Washington (CNN) Three more National Rifle Association leaders have stepped down, CNN has learned, in a broadening of a leadership exodus amid a controversy over the group's spending.

Country music singer and NRA board member Craig Morgan has resigned, sources with knowledge of the matter tell CNN, and NASCAR team owner Richard Childress stepped down on Monday. David Lehman, the deputy executive director and general counsel at the NRA's Institute for Legislative Action, also is leaving the organization, the sources tell CNN.

Both Morgan and Childress were prominent public faces for the NRA. Morgan appeared frequently on the group's now-defunct streaming video service NRATV and even hosted his own program on the network. Lehman was the deputy to then executive director Chris Cox, who resigned in June and was also the NRA's top lobbyist. Lehman was filling the role of top lobbyist when he departed the organization.

The departures are the latest to roil the organization's leadership, which has seen several members resign in recent weeks amid the controversy over NRA spending and the forced resignation of former NRA President Oliver North

CNN has reached out to both Morgan and Lehman for comment, and the NRA has not responded to multiple requests for comment.