Labour has been forced to defend an advert which appeared to suggest several large companies backed its business manifesto.
It quoted senior figures at firms including Kellogg's and Siemens supporting Britain in the European Union.
But as ITV News Political Correspondent Carl Dinnen explains, some of them are not happy.
Ed Miliband has warned that Tory plans to hold a referendum on Britain's membership with the European Union pose a "clear and present danger" to jobs and prosperity.
The Labour leader will use the first day of the official campaign period to warn that David Cameron's plans for a referendum in 2017 will lead to "two years of uncertainty".
In a speech at Bloomberg in London today, Mr Miliband will say businesses will face years of "chaos" and will be left unable to plan for the future if the the Tories win power on May 7 and the referendum goes ahead.
Miliband will say that his party will not "condemn this country to years of uncertainty, years of insecurity, by threatening our European future".
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Ed Miliband made some young supporters very happy as he accepted an opportunistic selfie request upon arriving to launch Labour's General Election campaign at London's Olympic Park.
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The Labour Party has admitted that Ed Miliband was caught up in "campaign rough and tumble" involving demonstrators yesterday - but denied claims its leader was punched in the chest.
The alleged incident was "shrugged off" by Miliband after taking place in London yesterday morning, the party said.
The Mirror had reported that around six demonstrators had surrounded the opposition leader.
The paper cited an activist who claimed: "Ed had to push his way through them to get into the car. It was over very quickly but it was shocking."
Miliband and Prime Minister David Cameron later appeared separately on television for a live question-and-answer session.
Lord Grade has alleged that broadcasters are threatening politicians "in an illegal fashion" over the TV debates.
The former BBC and ITV chairman told ITV News that he had become "appalled" by the wrangling over the debates.
Asked if he stood by comments he made in January that no leader should have the right to prevent the debates, the Tory peer told Chris Ship: "No I don't, I think that was wrong - if there is no consensus there shouldn't be any debates."
A joint statement issued by ITV, the BBC, Sky and Channel 4 says they are trying to deliver TV debates between party leaders "because we know our audiences want them."
It added: "In 2010 they were watched by more than 20 million people and our research suggests there is an appetite for them in 2015.
"We have issued invitations to seven party leaders and we continue to hope they will all agree to take part."
The comment was issued after former BBC and ITV chairman Lord Grade accused broadcasters of 'bullying' David Cameron over his reluctance to take part in what they have proposed.
Ed Miliband branded David Cameron's excuses not to engage in TV debates before the General Election as "feeble and pathetic".
There has also been a suggestion of a five-way leader online debate to solve Cameron and Miliband's "stalemate" position.
ITV News Political Correspondent Romilly Weeks reports.