Prime Minister Stephen Harper's chief of staff, who was accused of leaking a government memo that cast aspersions on US presidential hopeful Barack Obama, will soon resign, media said.  Reports said that Ian Brodie was planning to quit in July, just before a Privy Council and Foreign Affairs Department joint investigation reports on the possibly illegal leaking of the government memo.  A newspaper cites unnamed sources close to Brodie. The affair embarrassed Canada's diplomatic core and may have cost Obama votes in the crucial Ohio and Texas primaries in March.