KARL ROVE definately being looked at as possible source

...Under US law, it is a serious crime to reveal the identity of a covert US intelligence official, carrying a maximum sentence of 10 years in prison and $50,000 (£31,250) in fines.

If Mr Rove was implicated, it would seriously damage the president's standing at the start of his re-election campaign and rob him of an electoral mastermind who orchestrated his rise to the Texas governorship and then the presidency.

One veteran of the Clinton administration compared it to the Hutton inquiry. "In the Kelly case there's a body but no crime. Here there's no body but there is a crime," he said.

Ms Plame is the wife of Joe Wilson, a former US ambassador who in July accused the White House of misleading the nation over claims of Iraq's attempts to buy uranium in Africa. In a New York Times commentary he said he had been sent to Niger to check such claims in 2002 and found them to be baseless...

http://www.guardian.co.uk/usa/story/0,12271,1053191,00.html