A top advisor to US presidential hopeful Senator Hillary Clinton has resigned.
Mark Penn, who worked as the campaign's chief strategist, stepped down last night following revelations about his work on behalf of the Colombian government.
Mr Penn was a pivotal figure in the Clinton campaign and as chief strategist, he was responsible for many key decisions. He had previously worked on President Bill Clinton's re-election campaign in 1996 and he also worked on Hillary Clinton's senate campaign in 2000.
The immediate cause of his resignation was his meeting last week with the Colombian Ambassador to the US.
Mr Penn's company was engaged to lobby on behalf of Colombia for the passage of a trade deal, which is opposed by many Democrats including Senator Clinton.
Mr Penn continued to work as a lobbyist while chief strategist of the Clinton campaign.
In a statement last night, the Clinton campaign said Mr Penn's company would still provide polling and advice. It has already been paid $10m for its work on the campaign.
