Conservative leader David Cameron will rally party activists at the weekend, hoping to boost his poll lead over Labour with a series of family friendly policies.

At the party's spring conference, which starts in Gateshead on Friday, Cameron will promise to make parental leave more flexible as he seeks to broaden his party's reach with the electorate.

Mothers and fathers would be able to exchange and share their statutory rights to time off work under a scheme to ease the burden of child care.

The underlying focus of the two-day conference will be on the coming local elections and the race for the next Mayor of London.

Conservative mayoral contender Boris Johnson is running neck and neck with Labour incumbent Ken Livingstone in polls ahead of the May 1 election.

Elections are also being held in more than 160 local councils in England and Wales but most attention is being paid to the high profile battle in London.

The contest between Ken and Boris is being seen as a proxy for the general election, due by 2010 but potentially coming as soon as spring next year.

Cameron has maintained a lead of between four and nine points ahead of Labour since Prime Minister Gordon Brown ducked out of possible snap election last autumn.

But analysts say the Conservatives have no chance of winning an overall majority in parliament while they are stuck at current polling levels of around 40 percent.

John Curtice, professor of government at Strathclyde University, says Cameron needs to expand his poll lead significantly to have confidence of winning power.

"Every single opposition that has won government in the post-war period has actually hit 50 percent in the opinion polls at least at some point in the preceding parliament," he said.

"That gives you some idea of how far off the Tories are."

He said Cameron had failed to exploit the government's weakness over the economy and the nationalisation of mortgage bank Northern Rock.

"While the government has trouble with the economy, the Tories still have to convince that they can do a better job.

"On Northern Rock they played the classic opposition game of criticising everything the government did, but actually did they have a clear alternative? The answer is no."

But Nottingham University Politics Professor Philip Cowley said the Conservatives have no need to aim for an overall majority, although they might not admit it.

"The polls at the moment do show us heading for a hung parliament, but they also show us heading for a hung parliament with the Conservatives as the largest party," said Cowley.

"It seems to me, although no one will say this publicly, that that would be enough."

In such a scenario Cameron would be able to form an administration quite easily, he added.

"It wouldn't last for years, but it would last long enough. Then at some point, a year or two further down the line, Cameron would call another election."