Former FBI director James Comey suggested that Donald Trump’s move to separate migrant children from their parents — a policy the U.S. president hastily reversed on Wednesday —could be the most harmful misstep he has yet made to his administration.

“Every so often, the giant is awakened that offends no matter where you are – there’s good to come out of it (migration policy), it may be stirring the giant, that’s why Trump ran so fast and lied so much – one thing he is good at is sensing the giants awakening,” Comey told a London audience on Thursday at an talk sponsored by Intelligence Squared, a debate event organizer.

The White House did not immediately respond to a CNBC request for comment. It released a statement on Wednesday blaming Congressional inaction for the separations, saying that it is “the policy of this Administration to maintain family unity, including by detaining alien families together where appropriate and consistent with law and available resources.”

Polls conducted by CNN and Quinnipiac found that two-thirds of Americans are strongly opposed to the policy, with Democrats all strongly opposed, and Republicans split on the policy.

According to Pew Research Center data published two days ago, voter engagement is higher than in previous midterm elections, and Americans’ views of the president — negative or positive — are seen strongly influencing votes.

Referencing his book “A Higher Loyalty,” Comey referenced Trump’s

tweets calling for Comey’s incarceration

, stating that he refuses to become numb to Trump’s continual breaking of long-established standards, such as his recent hint at what to expect prior to a formal U.S. jobs report

Comey, a registered Republican until the 2016 election, said he will vote based on values rather than party affiliation in 2018.

Slamming Trump multiple times both on his personality and his strategy, Comey described his ideal candidate as one whose values are the opposite of Trump’s.

“The next president has to restore truth, rule of law, and equal protection of law, things at the heart of the U.S.,” Comey said.

Trump recently

tweeted his excitement about a jobs report prior to its release

. That move violated a protocol that was designed to prevent market-moving disclosures ahead of their formal publication. That prompted a shift in financial markets as traders planned for strong employment figures.

Comey didn’t reveal which political party he would vote for, but he talked a great deal about the values they should have in contrast to Trump.

Though the former FBI boss had a lot to say on Trump, he also stated that the Department of Justice was correct in finding his own actions “extraordinary and insubordinate” — but not politically biased — in the Hillary Clinton email investigation.

Comey is due to teach on ethical leadership this autumn at the William & Mary Law school.