A congressman’s letter that helped push a New Jersey attorney to resign after her boss was told she was a grassroots “ringleader,’’ has sparked questions about how much an employer can clamp down on an employee’s activism.

An ethics watchdog claims Rep. Rodney Frelinghuysen violated House rules by criticizing a local bank executive in a fundraising letter to her employer.

Campaign for Accountability asked the Office of Congressional Ethics to investigate whether Rep. Rodney Frelinghuysen (R-NJ) violated House ethics rules when he warned a banking executive that a member of an activist group opposing the congressman worked at Lakeland Bank in New Jersey.