In his first interview since his election, Donald Trump has said he would consider keeping parts of the healthcare law he vowed to repeal.
In the interview with the Wall Street Journal, he also said he had given only a little thought to appointing a special prosecutor to investigate Clinton.
Portland Police fired tear gas, pepper spray and rubber baton rounds after an anti-Trump rally descended into violence.
Officers declared a riot was in progress as protesters vandalised shops and cars, started fires in rubbish bins and threw objects at police.
Police closed down areas declaring it an "unlawful assembly" and reported "extensive criminal and dangerous behaviour". At least 29 people have been arrested.
Other protests have continued to take place elsewhere in the USA, including Chicago and New York, in opposition to Donald Trump who was elected as the next president on Tuesday.
The Ukip leader insisted that Donald Trump wants a "good" future relationship with the UK.
A spokesman said Mr Johnson, who has told his EU counterparts to stop the 'whinge-o-rama' over Mr Trump's election, would skip the meeting.
Many observers believe Donald Trump's administration could be the most controversial in US history.