Britain's trade unions are close to joining the push to keep the country in the European Union, bringing grass-roots muscle to a fight that has so far been dominated by big business and bankers, the head of the country's largest union group said. Unions will fight to stay in, emphasising jobs and workers' rights, Frances O'Grady, general secretary of the Trades Union Congress, said in an interview. Voters were not yet listening to the arguments because the campaign to date has had little to do with their everyday lives, she said.

"There is a real danger that this campaign is turning into a debate between elites funded by the big banks on the one hand and hedge funds on the other," O'Grady told Reuters, referring to some of the main financiers of the rival camps.

Opinion polls suggest voters are split almost 50-50 on whether to pull Britain out of the EU in a vote which Prime Minister David Cameron is likely to schedule for later this year. "What we need to do is start putting rights and jobs centre stage in the campaign debate," O'Grady said. "The bulk of the rights at work that matter to us originated in Europe."

Britain has around 6 million union members, half the number of the late 1970s. But the TUC, which represents most unions, remains a political force with close ties to the opposition Labour Party which is broadly supportive of EU membership. In a referendum in 1975, the TUC campaigned to get Britain out of what was then European Economic Community.

But it turned pro-Europe in the 1980s when Brussels promised to combine the allure for business of a single European market with strong protections for workers, something that contrasted with the bitter industrial conflict raging at the time between unions and former Prime Minister Margaret Thatcher.

In 2015, the TUC held off from promising to fight to keep Britain in the EU in protest at signs that Cameron wanted to water down the bloc's so-called Social Chapter incorporating workers' rights before he called the EU membership referendum. O'Grady said she was now confident that a weakening of protections such as guaranteed paid holidays and parental leave and health and safety rules would not be among the reforms Cameron is expected to clinch with other EU leaders next month. That means that all but a few of the 52 unions represented by the TUC are likely to urge voters to stay in the EU.

Brexit EU referendum
ICM poll found remain and leave is split 50/50 as David Cameron continues his renegotiationiStock

The EU-mandated protections for workers would be at risk if Britain votes to leave the EU. Many MPs in Cameron's Conservative Party resent them as an embodiment of EU over-reach into the affairs of member states. For the TUC, by contrast, they are sacrosanct.

"The TUC's assessment is that if Britain was to leave the EU there would be really big risk to rights that matter to people's real lives, from paid holidays to parental leave, health and safety at work, these are the sorts of rights that people depend on week by week," O'Grady said, referring to a possible British exit.

"If you take that floor away, workers will be worse off. It's a hell of a gamble for those who want to leave Europe, to depend on particularly the government we have now to protect the rights on which so many people's working lives depend."

The relationship between the EU and Europe's labour unions has come under strain in recent years. Many unions complain the bloc has taken an increasingly pro-business stance and were appalled by the austerity measures that it ordered for countries such as Greece, Spain and Portugal during the eurozone's debt crisis.

"I think that there is a real risk that some of that anger that ordinary people have felt ever since the crash and ever since they've been suffering a decade of lost wages will end up being put on the EU and potentially people saying we are better off out. I think it puts a heavy responsibility on politicians to start coming up with some answers," she said.

O'Grady said Brussels had to show disillusioned voters that it could help them by spurring Europe to create more and better jobs. And, in an increasingly competitive global economy, Europe represented the best bet for Britain's workers.