Supporters of Kenya's proposed constitution tried to disrupt a rally by their opponents at the weekend. (Photo Courtesy Julius Sigei)

The bitterly fought campaign over Kenya's proposed new referendum reaches its climax Sunday with rallies by both sides in Nairobi and accusations of dirty tricks by opponents of the changes.

There will be further meetings Monday before voting on the proposed referendum takes place on Wednesday.

Popular support for the new constitution was supposed to be a fait accompli. That was until the mainstream churches threw a spanner in the works. They mobilised for a rejection of the draft, claiming that it is liberal on abortion and same-sex relationship and that it introduces Muslim Khadi courts.

Former President Daniel Arap Moi and influential politicians from the populous Rift Valley province are opposing the draft over the same issues and over the question of land.

President Mwai Kibaki, Vice President Kalonzo Musyoka, Prime Minister Raila Odinga and nearly 90 per cent of the cabinet and MPs addressed a huge rally in Nariobi's Uhuru Park, urging a massive turn-out in favour of the draft.

The no campaign held a similar rally in the city's Jamhuri Park. They accuse the government of using underhand methods and intimidation to get support for the draft because it senses defeat.

Tom Namwamba, who heads the no campaign secretariat, claims that the president's side of using underhand tactics. They have used thugs to attack his office and steal material, he says, ordered civil servants to campaign for a yes vote and booked all choice venues in Nairobi to deny his side a convenient venue to hold their rallies.

"If you see anybody engaged in such petty, barbaric practices, then you know that that person has read the signs of losing," he comments.

But Kenya's Medical Services Minister Peter Anyang Nyong'o, who is also Secretary General of Prime Minister Raila Odinga's Orange Democratic Movement, says there is majority support for the draft.

First, from the genuine opinion polls, the yes is at the moment rated at between 66 per cent and 68 per cent, the no at between 18 and 20 and the rest are undecided," he says. "Over the last two weeks the undecided have been moving gradually to the yes side."

The two sides will conduct final rallies Monday, with President Kibaki hoping that Kenyans will endorse the realisation of a new constitution under his watch, allowing him to make history in the process.

Listen to a report on campaign rallies in Nairobi here.

Listen to Rev Oliver Kisaka of the National Council of Churches of Kenya for the No campaign here.