Coca-Cola is battling to head off the threat of losing its £7 million a year contract to supply its drinks to students at 200 universities and colleges in the UK.
The National Union of Students will consider a nationwide boycott of the firm at its conference next month in protest at alleged human rights violations in Colombia and environmental damage in India.
The boycott is being urged by individual university student unions such as York, but the commercial arm of the NUS is arguing that "constructive engagement" is the best way to influence the company's ethical policies.
NUS Services Ltd, which negotiates on behalf of student-run bars and shops across the UK, wants to renew the contract for three more years this summer.
Ian King, chief executive of NUSSL, said: "We believe we have made and can make progress through an agenda of constructive engagement rather than through a boycott." But he added: "There is no silver bullet. There is no evidence to support either side."
Confronted by decisions by ten US universities, including Michigan and New York, to pull its products off the shelves, Coca-Cola announced last month that it would co-operate with an independent review of allegations that it had not done enough to stop violence against union workers in Colombia. It also promised an audit of its labour relations and environmental policies globally.
NUSSL said that the cost of entering the student market - £1 million in bar and shop equipment - would deter rivals such as Pepsi-Cola, the only alternative with the capacity to meet demand, or smaller players such as Virgin.
Mr King said: "None of the others can give us the national capacity to deliver, nor do they have the £1 million to spend on the market."
A Coca-Cola Great Britain spokesman said that in more than two years of constructive engagement with the NUSSL, a number of major changes had been made in the way the company operated.
The ethical committee of the NUS will report to the union's conference next month on the constructive engagement policy, two weeks before the NUSSL decision.