Prime Minister David Cameron promised to hand almost half the British population a tax cut if re-elected next year, a pledge he hopes will win over millions of voters and refocus debate away from a schism inside his party over Europe.

The promise, which will cost over £7bn to fund, was a calculated gambit to try to shift the narrative from one which has focused on the damage the anti-EU UK Independence Party (UKIP) is doing to Cameron’s re-election hopes by siphoning off voters and lawmakers.

It was also an attempt to kick-start his Conservative party’s moribund rating in opinion polls, where it has been trailing the opposition Labour party for months, by holding out the prospect of a sweetener to balance a less enticing promise to freeze most welfare pay cheques and to slash state spending.

“So Britain: what’s it going to be?” Cameron, 47, asked supporters packed inside a concert hall at his party’s annual conference in the central English city of Birmingham. “I say: let’s not go back to square one. Let’s finish what we have begun.”

In a speech which touched on Scotland’s decision to remain in the UK, the threat posed by Islamic State, and Britain’s Second World War role, Cameron told activists he wanted and needed to be re-elected with an overall majority so he could govern alone and not in a coalition as is now the case.

“Believe me: coalition was not what I wanted to do; it’s what I had to do,” he said. “And I know what I want next. To be back here in October 2015 delivering Conservative policies.”

Cameron has endured a tumultuous month taking Britain into battle with Islamist militants in Iraq, pondering his own demise if Scotland had voted to leave the United Kingdom, and watching as two of his lawmakers quit to join the anti-EU UKIP party.

In his speech he tried to strike a calm statesman-like posture as he sought to shore up his leadership, steady his party, and dangle some eye-catching promises before voters.

The centrepiece was a promise to lift one million workers out of tax if re-elected by allowing them to earn more before they pay any income tax, a pledge he said would also mean reduced tax bills for 30 million more people, or just under half the country’s total population.

He also pledged to ease the burden on the middle class by raising the threshold for the country’s 40 per cent rate of income tax.

“With the Conservatives, if you work hard and do the right thing we say you should keep more of your own money to spend as you choose,” Cameron told delegates to applause.