Sen. Jeff Flake (R-AZ) on Monday said members of his own party have “have maintained an unnerving silence as instability has ensued” under President Donald Trump’s administration.

“With hindsight, it is clear that we all but ensured the rise of Donald Trump,” Flake said in an excerpt published by Politico of his upcoming book.

He cited Republicans “who, upon Obama’s election, stated that our No. 1 priority was not advancing a conservative policy agenda but making Obama a one-term president,” as well as those “who were largely silent when the most egregious and sustained attacks on Obama’s legitimacy were leveled by marginal figures” — including Trump.

“It was we conservatives who rightly and robustly asserted our constitutional prerogatives as a co-equal branch of government when a Democrat was in the White House but who, despite solemn vows to do the same in the event of a Trump presidency, have maintained an unnerving silence as instability has ensued,” Flake said.

Flake, who is up for reelection in 2018, said he was “sympathetic to this impulse to denial” but called it “a monumental dodge.”

“To carry on in the spring of 2017 as if what was happening was anything approaching normalcy required a determined suspension of critical faculties. And tremendous powers of denial,” he said.

Flake on Sunday similarly criticized Republicans for being “complicit” if they do not speak out against President Donald Trump’s actions or behavior when they disagree.

“That unnerving silence in the face of an erratic executive branch is an abdication,” he said in the excerpt published Monday. “And those in positions of leadership bear particular responsibility.”