The U.K. prime minister will be using MSN Messenger to chat with 10 members of the public, who will be invited to put questions to him over IM.
Microsoft is asking would-be politicos to submit their questions on MSN's U.K. Web site. The software maker will pick the winners, who will be able to ask the question via IM video conversation.
Blair is particularly interested in being grilled on Africa and climate change, MSN said.
Previously, the prime minister has pressed the virtual flesh using, where the electorate asked Blair's opinions on subjects such as Iraq and his favorite guitar solo.
Jo Best of Silicon.com reported from London.