Mr Tudjman, long rumoured to be suffering from cancer, underwent emergency intestinal surgery last Monday. His doctors said yesterday he was in a stable condition.
A spokesman for Mr Tudjman's party, Ivica Ropus, insisted after the poll was published that the 77-year-old President will "actively participate" in the party's campaign for the parliamentary elections, scheduled for 22 December.
The party's popularity has declined rapidly in recent years, but a number of Croats still support Mr Tudjman, whom they credit with leading the country to independence in 1991.
His appearances in the election campaign could attract more votes for his Croatian Democratic Union.
Mr Tudjman, whose mandate runs until 2002, has denied having cancer. (AP)