WASHINGTON - A Donald Trump supporter who posted pipe bombs to Barack Obama and Hillary Clinton has been sentenced to 20 years in prison.

Cesar Sayoc, 57, also admitted sending the devices to former vice president Joe Biden, several members of Congress, and the Hollywood actor Robert De Niro.

Devices were also mailed to the offices of the news channel CNN in New York and Atlanta.

Sayoc wept and crossed himself, appearing relieved, when US District Judge Jed S Rakoff handed down the sentence.

The judge also concluded that the bombs were not designed to explode.

Prosecutors had urged a life prison term for the amateur bodybuilder, who pleaded guilty this year after mailing the 16 pipe bombs days before mid-term elections last

The judge said: "He hated his victims, he wished them no good, but he was not so lost as to wish them dead, at least not by his own hand."

The former stripper and pizza delivery man from Aventura, Florida, apologised to his victims saying he was "so very sorry for what I did".

Assistant federal defender Marcus Amelkin said Sayoc was obsessed with President Trump and grew to believe Democrats were to blame for damage to his van,
which was plastered with Trump stickers and images of crosshairs superimposed over the faces of the president's opponents.

Sayoc "looked up to the president as a father figure", the lawyer said.(FA)