Liberal Leader Michael Ignatieff has accepted an offer from comedian Rick Mercer to take part in a one-on-one debate with Conservative Leader Stephen Harper.

Harper has yet to respond to the popular television personality, who mused on his Twitter account on Friday night about moderating a debate between the two leaders.

Harper had earlier spoken about the possibility of a one-on-one debate, but then distanced himself from the idea and said he accepts the judgment of the broadcast network consortium to have two four-leader debates.

Mercer tweeted late Friday night that he would rent Toronto's Massey Hall for the showdown.

"Ok hell i will rent massey put the cameras in place and moderate the Harper Iggy smackdown," Mercer tweeted.

He followed it several minutes later with "Ok i'll produce a Iggy Harper debate. 50 grand to a charity of their choice. I'll find a broadcaster or 4."

Ignatieff responded Saturday afternoon, also on Twitter: "I'm in."

The Liberal leader then tweeted that he wanted the charity money to go to the Alzheimer Society. Ignatieff's mother succumbed to Alzheimer's disease in 1992.

The broadcast consortium debates involving Harper, Ignatieff, NDP Leader Jack Layton and Bloc Québécois Leader Gilles Duceppe will take place April 12 in English and April 14 in French.

The broadcast consortium comprises representatives of CBC/Radio-Canada, CTV, Global and TVA. Both debates will take place in Ottawa. The English debate will be moderated by TVO journalist Steve Paikin, while the French debate will be co-moderated by Radio-Canada's Anne-Marie Dussault and TVA's Paul Larocque.

Both Layton and Duceppe have dismissed the idea of a one-on-one debate between Harper and Ignatieff.