David Cameron has launched a major push to win support for his call to keep Britain inside what he says is a "reformed" European Union.

The British prime minister plans TV appearances Sunday to argue that his country's interests are best served by a vote to remain in the EU in the June 23 referendum.

He is opposed by Justice Secretary Michael Gove and several junior ministers. London Mayor Boris Johnson has yet to announce his stance.

Cameron is challenging forces that support a British departure from the EU, dubbed Brexit, by asserting such a move wouldn't slow the flow of migrants into the country.

He says any new trade deal forged with the EU if Britain left would have to include free movement of labor to meet Brussels' demands.