What the ground for impeaching them?

Grounds for impeachment typically include "high crimes and misdemeanors," as outlined in the U.S. Constitution. This can encompass a wide range of misconduct, including abuse of power, bribery, corruption, or violations of public trust. Impeachment is a political process, often driven by allegations that a public official has acted in a manner that undermines their duties or the integrity of the office they hold. Ultimately, the specific grounds for impeachment depend on the circumstances and evidence presented by lawmakers.