Prime Minister David Cameron and Deputy Nick Clegg will go head-to-head today in a battle over the electoral system.

While the PM wants to keep the current “first past the post” system, Clegg is pushing for the Alternative Vote (AV), where voters rank MP candidates by preference.

Mr Cameron will make a speech today, arguing his point that AV makes it more difficult for voters to oust an unpopular government, saying that it could have led to Gordon Brown continuing in No 10 after last year’s election.

Cameron said: “The simple fact is, AV could exaggerate the inherent biases in the current system, giving Labour an even bigger advantage than they already have at general elections,” he said in a speech in central London.

“Yes, our politics needs reform. Yes, we need to shift more power down across the country.

“But no to AV. It means a voting system that is unfair, processes that are unclear, and politics that is unaccountable. It is, put simply: the precise opposite of what we need right now.”

Meanwhile, Clegg will argue that the current system is outdated.

He said: “First past the post is out of date and it is at the heart of so many of the reasons that people don’t trust in or care about politics.

“It makes it easy for MPs to get complacent and lazy. First past the post is not working and it’s time to get rid of it.

“The alternative vote puts you back in charge. You get a bigger say in who your MP is. A bigger foothold in our democracy. A bigger stake in our country.

“The alternative vote is a simple change that will make a huge difference. It means MPs working harder, more voices being heard and power put back where it belongs – with you.”