The new Conservative Party leader should stick with "mainstream" Eurosceptic opinion, says former Tory chief Iain Duncan Smith.
Duncan Smith warns of Euro sceptic fringe parties taking the lead.
"To do otherwise would allow Labour to escape the dock of British public opinion," he will say in London.
He is to argue Tony Blair should not be let "off the hook" over the EU treaty.
In a speech to be made to the Swedish Chamber of Commerce, the ex-leader appears to attack pro-Europe leadership contenders such as Ken Clarke.
Mr Duncan Smith will address members of the Swedish business community on the international and domestic implications of the rejection of the proposed EU Constitution by France and the Netherlands.
He will use the opportunity on Friday to signal his views on the potential successor to Michael Howard.
"Whoever becomes the next leader of the Conservative Party must continue to lead from the mainstream of Eurosceptic opinion," he will say.
"To do otherwise would allow Labour to escape the dock of British public opinion and surrender the task of chief prosecutor to fringe Eurosceptic parties."
Mr Duncan Smith will suggest selecting a Europhile as the next Tory leader could mean a return to "anguishes over Europe".
"The Conservative Party became united on the European issue because it began to be led by people who shared the Eurosceptic instincts of 90% of its members and of the clear majority of the British people."
He is to say the Tory party was "almost alone" amongst Europe's mainstream parties in opposing the "undemocratic nature" of the EU constitution.
The rejection by France and the Netherlands is not, he will say, about the Conservatives being off the hook.
"It's about putting and keeping Tony Blair on the hook. Europe is in crisis and Tony Blair is part of the problem."
He will call on both Prime Minister Tony Blair and Chancellor Gordon Brown to "give the British people their opportunity to reject the Treaty".