The head of a campaign for the UK to remain in the EU has predicted his side will win the referendum "by a substantial margin".
Lord Rose is confident "common sense will prevail" in the vote and denied his group represents "project fear".
The Tory peer and former Marks and Spencer boss chairs the cross-party Britain Stronger in Europe campaign.
EU exit campaigners dismissed his remarks, saying the "cosy establishment club" did not want change.
Opinion polls have been inconclusive so far, with those conducted over the internet tending to show growing support for British exit, but phone polls suggesting the Remain campaign is comfortably ahead.
In the latest YouGov internet poll, in The Times, 45% of those polled want Britain to leave, an increase of 3%, with 36% wanting to remain, down 2%, and 19% don't know or won't vote, down 1%.
The poll was taken after David Cameron unveiled his EU reform deal.
'Beating the drum'
The prime minister is attempting to persuade other EU leaders to back the package of reforms he has hammered out with European Council president Donald Tusk.
The draft deal, which the PM hopes will keep the UK in the EU, has been dismissed as meaningless by campaigners to quit the EU
Lord Rose described the package, including curbs on EU migrants' benefits, as a good deal but said it was "probably not" perfect.
Once a final deal has been sealed, the prime minister will announce the date of the UK's referendum - with June seen as the most likely month.
Pressed on what he thought the final result would be, Lord Rose said: "A win is a win. If we get to 50.001% it is a win.
"I want to win, but we will win by a substantial margin."
He added later: "I think if we just keep going, beating the drum and saying what the facts are then common sense will prevail."
Matthew Elliott, the chief executive of Vote Leave, which is competing with Leave.EU to be the official campaign to quit the EU, said: "The cosy establishment club doesn't want change because it does well out of the status quo.
"But the people want change and to take back control. It's a David v Goliath struggle - but we all know who ended up winning that one."
A row has erupted between the two groups vying for official designation from the Electoral Commission - which brings access to public funds, TV broadcasts and a £7m spending limit.
Vote Leave shifted the two men running its operation, Mr Elliott and Dominic Cummings, to less high profile roles and appointed Tory peer Lord Lawson as its chairman.
This was initially welcomed by rival group Leave.EU, which said it had removed two "major obstacles" to them working together.
But after Vote Leave's Steve Baker rejected the idea of a merger, saying differences remained on tactics, Arron Banks, the UKIP donor behind Leave.EU, accused Vote Leave of "jeopardising this historic referendum" with their "unwillingness" to work with other groups.