House Oversight Committee Chairman James Comer (R-KY) has promised more evidence in President Joe Biden‘s impeachment inquiry for months, and some Republicans are growing restless about the lack of proof showing misconduct by the president.

Despite formalizing the impeachment inquiry last month into whether Biden improperly benefited from his son Hunter’s foreign business dealings in Ukraine and China, Comer’s leadership in the yearslong investigation is being questioned by Republicans, as no evidence of high crimes and misdemeanors has been produced.