Empowered by a new chief of staff and goosed by a president angry with a perceived lack of creativity, National Security Adviser Lt. Gen. H.R. McMaster is sweeping out some of the White House’s most fervent ideologues.

But McMaster has to move fast, senior administration officials tell The Daily Beast. Because the hardline nationalists at the core of Trump’s political base have declared war on the president’s top national security aide. His own role is by no means secure.

“The president hasn’t liked the plans he’s been presented on Iran, Afghanistan, or ISIS,” one of the officials told The Daily Beast. “The process hasn’t worked like it should,” to produce the innovative plans President Donald Trump tasked his team with crafting—plans that look different from what the Obama administration, or even the Bush administration, tried before.

So McMaster has been removing anyone on his team who either obstructed his own vision or had trouble rallying the other agencies around particular policy, like NSC intelligence director Ezra Cohen Watnick, who was let go on Wednesday.