"I tell you Sean, I'm to the point that I think Mitch McConnell, to really bring unity to the Republican Party and get things done, I think Mitch McConnell ought to tender his resignation," Bannon told host Sean Hannity on Fox News's "Hannity."
Bannon said while McConnell should not leave his post as majority leader during the tax push, he should provide his resignation this week.
"I think Mitch McConnell, tomorrow, should tender his resignation," Bannon said.
Bannon argued that McConnell has refused to take up bills in the upper chamber that could help oust red-state Democrats in the 2018 midterm elections.
At the end of the television appearance, Bannon said McConnell should provide his resignation Wednesday evening.
The comments from one of President Trump's former top aides come as Senate Republicans prepare their own tax-reform bill that is expected to differ from the legislation currently in the lower chamber.