When Nigeria's President Olusegun Obasanjo assumed office in 1999 he and Nigeria Labour Congress (NLC) leader Adams Oshiomhole were close allies.
Their relationship was so cordial, the BBC's Sola Odunfa in Lagos says, that the newly installed government and the 29-union umbrella body soon negotiated a 25% wage increase for public sector workers.
Oshiomhole was arrested recently
In return Mr Oshiomhole defended President Obasanjo in public and endorsed his candidacy when he was re-elected in 2003.
However, since then their relationship has soured over oil and even led to Mr Oshiomhole being called the unofficial leader of the opposition.
Their main falling-out is over the government's determination to drastically cut fuel price subsidies as part of attempts to deregulate the oil industry.
But the unions are also angry at the failure to maintain refineries which means most oil products, such as petrol, are imported.
The country is comfortably Africa's largest oil importer yet some two-thirds of the population live in poverty.
Many Nigerians feel the only benefit they see from their country's oil wealth is cheap subsidised fuel and the announcement of 25% price rises caused enormous resentment.
There is little doubt, says our reporter, that Adams Oshiomhole has proved that he has the trust and the confidence of Nigerian workers.
The unions have called three general strikes and forced temporary climb-downs from the government during the first two.
But things have steadily got nastier.
Mr Oshiomhole has faced arrests, tear gas and temporary blockades of union offices and after the last one in June, Mr Obasanjo introduced legislation to cut the powers of the NLC to make it more difficult for them to strike.
Yet his apparently committed leadership of the strikes has drastically increased his profile and standing.
The father of five rose through the ranks in the Nigeria labour movement after beginning his career as a shop steward at a textile factory.
In his march to the top he studied labour, economics and industrial relations at Ruskin College, Oxford in the UK and he also attended Nigeria's prestigious National Institute for Policy and Strategic Studies.
Our reporter says he is a very fluent and persuasive public speaker. He is also a pleasant person to meet but a very powerful individual.
He spends nearly all his time on union matters. About four years ago he told the BBC that his goal in life was to build the labour movement into a stronger and more cohesive force then when he joined.
And he appears to be succeeding because in 2002 the formerly fractious unions unanimously gave him one more term in office to strengthen the NLC.
His public image is summed up by a young bank employee in Lagos, who said: "Mr Oshiomhole commands respect".