DAR ES SALAAM - The east African nation of Tanzania marks its 50th birthday this weekend, but celebrations are being overshadowed by a tussle over the union between the mainland and the islands of Zanzibar.
Tanzania was born in 1964 from the marriage of Tanganyika and the Zanzibar archipelago following their independence from Britain.
It has proved to be an uneasy relationship -- with mainlanders determined to maintain national unity but many islanders still resentful over what they say was a shotgun wedding.
The midlife crisis has proved to be an unwelcome distraction for the government of President Jakaya Kikwete, who has been keen to champion the country as a pillar of stability and a future economic giant with large amounts of under-developed land, abundant natural resources such as gold, nickel and Tanzanite, a bustling tourism industry and the recent discovery of offshore natural gas.
"I don't think the union is as stable as it was in the past, because in the past three years people have been discussing an alternative structure," said Abdul Sheriff, a former professor of history at the University of Dar es Salaam.
In 2011, the government agreed to review the status quo and draft a new constitution, with a special team touring Tanzania's crammed cities, isolated savannah outposts and white sand beaches to get a sense of the public mood.
Last month a new draft was brought before a 600-plus-member Constitutional Assembly for debate ahead of a planned referendum.
The draft constitution suggests a new federation made up of three distinct governments: autonomous authorities for Zanzibar and the mainland, and a smaller union government to deal with federal matters such as defence and foreign affairs.
This contrasts with the current structure of a Tanzanian union government and an autonomous Zanzibar government -- a structure that the government wants to keep even though it is criticised by islanders who say they have no real power in the face of the far larger and richer mainland.
Zanzibaris also consider themselves unique from those on the mainland. Predominantly Muslim, the population is a cosmopolitan mix of Arabs, Asians and Africans and has been doing a steady trade in spice -- and, for a time, slaves -- for over a thousand years.
"If the alternative is pursued, then the union might become stable," said Sheriff, a member of the constitutional assembly and supporter of reforms.
"But if the government succeeds in reversing it, changing it, then the people might vote against it. And if that happens, that could be very dangerous," he said, citing the risk of political violence like that experienced amid neighbouring Kenya's political turmoil of 2007.
Off to a bad start
But the debate on reforming the union ran into trouble almost as soon as it started.
Earlier this month, close to 200 of the constitutional assembly members -- mostly from opposition parties and many representatives of Zanzibar -- quit the proceedings in protest over being bullied by the ruling Chama Cha Mapinduzi (CCM) party, which controls nearly two-thirds of the assembly.
"One third of the members have walked out. And if they don't go back then no constitution can be passed at the present time," said Sheriff, who was one of the members who walked out.
"Whether the union survives for another 50 years depends on whether we find a suitable structure with which both sides can live. And for that we'll have to see."
Kikwete, however, argues that the three-government system would be too expensive and might even end up destroying the union altogether.
"If you decide to start segregating each other today, things will be difficult," Kikwete warned last month.
Because of the walkout, the assembly no longer has enough representatives from Zanzibar to legally review the draft constitution, according to Bernadeta Killian, a professor of political science at the University of Dar es Salaam and another assembly member.
"And if the ruling party pushes the draft through without the opposition parties' involvement, the process will lack legitimacy. So the direction of the union is uncertain at this time."
Despite all the fighting, Killian believes that the rocky process is healthy.
The people of Zanzibar were never consulted about whether they wanted to join the union in the first place. Fifty years later, they finally have a chance.
"This is the first time that we've had an open discussion about the union. A lot of things that were swept under the carpet or done behind closed doors and now being discussed out in the open," said Killian.
"There have been problems since 1964 and every time people have predicted that the union would collapse. But it has survived. If we get out of this intact, the Union will be stronger than ever before."
Tanzania marks 50th independence anniversary