The winner of the 10 million Swedish crowns ($1.32 million) prize, perhaps the world's most coveted accolade, will be announced in Oslo on Friday at 0900 GMT. There are 165 candidates in the race.
“We've had a lot of interest in the Pope,” Gerard Daffy, at Australian-based Centrebet bookmakers, told Reuters.
“We're offering US President George Bush and British Prime Minister Tony Blair at 200-1 but haven't had a single bet,” he added.
“This is the man of the century, not someone who has done something only the past one or two years. Havel is inspiring”
Centrebet had the Pope on Thursday at 5-2 on. That means the punter get $1.40 for every $1 bet if he wins.
Havel, who facilitated the collapse of communism in Eastern Europe in the late 1980’s with his “Velvet Revolution”, trailed him at 7-1 with Irish rock star Bono and Brazilian President Luiz Inacio Lula da Silva tied on 10-1.
The ailing Pope, who celebrates the 25th anniversary of his election this month, won praise this year for preaching reconciliation and for trying to ensuring that the US-led Iraq war was not widely interpreted as a crusade by Christians against Muslims.
Commenting on rumours that the Pope's health is deteriorating, Daffy pointed to the Nobel rule that forbids awarding the prize posthumously.
“Given the pontiff's poor health, this may be the Norwegian Nobel Committee's last chance to honour his tireless work,” he said.
Still, some Nobel watchers think the pontiff is too controversial a figure in liberal Norway to win the award. They say dissident-turned-president Havel is a safer bet.
The Pope has come under repeated criticism for opposing the use of condoms, especially to slow the spread of AIDS.
Pope John Paul II increasingly
stricken with Parkinson's disease
One of Europe's leading playwrights, Havel - a dissident voice and writer during the Prague spring of 1968, co-author of the human rights manifesto Charter 77 and political prisoner - was swept to power after Czecholosvakia's 1989 “Velvet Revolution.”
Experts believe that awarding the prize to 67-year old Havel would send a special signal to eastern and central Europe's new democracies, just as the European Union is on the verge of expanding eastwards with 10 new members.
Irwin Abrams, a US authority on the award, said he favoured Havel - who has been nominated many times before and who stepped down as Czech president in February.
“This is the man of the century, not someone who has done something only the past one or two years. Havel is inspiring,” Abrams told Reuters.
“The Pope has certainly been an important influence for world peace, but many would feel that his conservative theological doctrines have stood in the way of the Catholic Church's progress in today's world,” he added.
Also in the running, according to Centrebet, are Iranian dissident Hashim Aghajari, the European Union (EU), French President Jacques Chirac, former UN weapons inspector Hans Blix and International Atomic Energy Agency head, Muhammad El Baradei.
Australia’s war-mongering Prime Minister, John Howard, is at 500-1, British Prime Minister Tony Blair and US President George Bush are both at 200-1.
Previous winners have included United Nations Secretary General, Kofi Annan, the charity Medecins Sans Frontieres and Nelson Mandela.