The envoy leading President Donald Trump's hardline push on Iran quit on Thursday, months before an election that could reorient US policy. Brian Hook, a stalwart Republican considered one of the most powerful figures at the State Department, decided to return to the private sector, Secretary of State Mike Pompeo said. Hook "has achieved historic results countering the Iranian regime," Pompeo said in a statement. Hook will be replaced by Elliott Abrams, an intellectual architect of the 2003 invasion of Iraq who has been leading Trump's unsuccessful campaign to oust Venezuela's leftist president, Nicolas Maduro. Abrams will handle both Iran and Venezuela, Pompeo said.