Tito Botelho Martins has endured a string of long and difficult winters in Canada. Now he's in line for a triumphant return to sunny Rio de Janeiro.

The Toronto-based executive is being touted as the leading candidate to replace Roger Agnelli as the chief executive officer of Brazil's Vale SA , the world's top iron ore producer and one of the biggest mining companies on the planet.

Mr. Agnelli, the flashy former investment banker who has steered an aggressive decade-long expansion of Vale's international operations, has fallen out of favour with Brazil's government over corporate strategy. Unhappy with Mr. Agnelli's perceived failure to invest enough in Brazilian mining and steel projects, Brazil's President Dilma Rousseff is understood to be using the government's leverage as a key shareholder of Vale (through state pension funds), to force Mr. Agnelli to step aside.

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Newspaper Folha de S.Paulo reported that Mr. Martins, who was parachuted in to run Vale's nickel and copper mining business from Toronto in early 2009, will be named Vale's new CEO.

A physically imposing and forthright veteran executive, Mr. Martins has presided over a tumultuous and controversial period for the mining operations that were once owned by Canada's Inco.

Workers in Sudbury, Ont., and in Voisey's Bay, Nfld., went on strike for more than a year over Vale's demands to reduce compensation and pension benefits. During the bitter labour dispute that stretched from 2009 into 2010, Mr. Martins made few friends among members of the United Steel Workers, which represented more than 3,000 striking employees. But he did gain some respect.

Wayne Fraser, a USW director represent the Sudbury workers, described Mr. Martins as "very articulate, knowledgeable and tough."

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The union official suggested that the company's high-profile labour troubles in Canada are partly responsible for the attempted ouster of Mr. Agnelli.

"What Vale was doing in Canada was not only having an effect on the company but was also having an effect on Brazil," Mr. Fraser said.

Mr. Martins was a key player in Vale's $19-billion takeover of Inco in 2006. He acted as liaison between the Brazilian mining firm, then known as Companhia Vale do Rio Doce, or CVRD, and government officials in Ottawa, including Industry Canada, which approved the buyout under Investment Canada's foreign takeover rules.

Vale had promised not to lay off workers for three years, but during the global financial crisis in 2009 it cut 463 Canadian jobs, citing plunging demand for nickel. Industry Minister Tony Clement said he was satisfied that the company had lived up to its undertakings because work-force reductions were being made across Vale's international operations.

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"From our membership and our community there is not a lot of trust in Tito Martins. But we can't look in the past, we have to look to the future and if he is appointed CEO, hopefully a new relationship can be forged," Mr. Fraser said.

Vale would not comment on the reports of Mr. Agnelli's looming exit nor on the possibility of Mr. Martins being named his replacement. Mr. Martins is currently in Brazil.

One Vale employee, who spoke on the condition of anonymity because the company has prohibited staff from talking to the media, said Mr. Martins is well liked and respected at the company's Toronto office.

"If Tito is the guy, it is good for us. He knows Canada, he knows the dynamic here. People will have their views on the labour dispute but the truth is he has the most intimate knowledge of the base-metals business in the organization," they said.