The US special envoy to Northern Ireland Mick Mulvaney has resigned from his post.
Mr Mulvaney, a former chief of staff to President Donald Trump, told CNBC he "can't stay" in the role following chaotic scenes of rioting in Washington DC.
A violent throng of pro-Trump rioters spent hours on Wednesday running rampant through the Capitol.
A woman was fatally shot, windows were smashed and the mob forced shaken legislators and aides to flee the building, shielded by Capitol police.
"We didn't sign up for what you saw last night," he said.
"We signed up for making America great again, we signed up for lower taxes and less regulation. The president has a long list of successes that we can be proud of.
"But all of that went away yesterday."
Mr Mulvaney said President Trump was "not the same as he was eight months ago".