Tories face a backlash after an online ad hailed bingo and beer tax cuts as "helping hardworking people do more of the things they enjoy".
The Scottish Parliament could gain more power over tax if voters reject independence, David Cameron has suggested.
MP Peter Bone insists he is "totally innocent" of allegations of benefit fraud, after his home was raided by police.
As many as 100 Tory MPs could be preparing to defy the party leadership by making a personal pledge to vote for a British exit from the EU in an in/out referendum.
The Independent reports that the eurosceptics are prepared to promise to vote 'No' to EU membership regardless of what concessions David Cameron can win from Brussels.
The Prime Minister has pledged to renegotiate the terms of British membership and then give the British people an in/out referendum in 2017.
One backbencher, Rochester MP Mark Reckless, told the paper: “My election manifesto will confirm my view that we should leave the EU.”
It is thought many Tory MPs consider making such a pledge the only chance they have of holding on to their seats in the face of a surge in support for Ukip.
Conservative MP Chris Kelly has announced he will stand down from his Dudley South seat at the 2015 general election.
The 36-year-old will be leaving Parliament after just one term, having won the constituency from Labour in 2010.
In a statement on his website he said he was "proud to have served the good people of Dudley South for the past five years" but did not give a reason for his decision.
Ukip leader Nigel Farage said a by-election win for his party in Clacton would signal a "landslide in British politics".
The Conservative Party is set for a humiliating defeat to Douglas Carswell - who resigned from the Tories - according to an opinion poll in the Mail on Sunday, which gave Ukip a massive 44 point lead.
Mr Farage predicted a Ukip win would result in "more and more people coming over to us" and predicted the party could hold the balance of power after the next General Election.
– Nigel Farage speaking to the Sun on Sunday
This is the moment. If we win the by-election in Clacton, it will create a landslide in British politics. If we lose, then selling ourselves as a party that can win a significant number of seats will get a lot harder.
He added: "If Douglas wins this by-election, then there will be more and more people coming over to us. We could end up holding the balance of power by next May."
Ukip look set to win the Clacton by-election convincingly, according to a new poll.
The by-election follows the decision by MP Douglas Carswell to defect from the Conservatives to Nigel Farage's party.
The Survation poll for the Mail on Sunday has Ukip on 64%, way ahead of the Tories on 20%, with Labour on 13% and the Lib Dems on just 2%.
Mr Carswell's personal appeal has helped the Ukip cause, with one in three respondents (34%) saying they would vote Ukip because they like him.
The family of former Conservative minister Sir David Mitchell, who died aged 86 following a long illness, have paid tribute to the health professionals who looked after him.
– A family spokesman
Sir David Mitchell, the former Member of Parliament for Hampshire North West and minister in the Thatcher governments has died today aged 86.
The family has expressed its gratitude to the health professionals and carers who enabled him to die peacefully in his own home.
Former Conservative minister Sir David Mitchell has died aged 86 following a long illness, his family has announced.
Sir David, who served under Margaret Thatcher in various departments including industry, transport and Northern Ireland, was the father of former Cabinet minister and current Tory MP Andrew Mitchell.
He was an MP from 1964 to 1997, representing Hampshire North West, and died at his home in Odiham, Hampshire, in the early hours of this morning.
Roger Lord, who had been the Ukip general election candidate for Clacton until Douglas Carswell jumped ship yesterday, has called the Tory defector an "idiot".
"If somebody pushes me, I'm going to push back," he said. "Has he [Carswell] got a membership card? I'm not sure he's officially a member yet."
Mr Lord told ITV News Political Correspondent Libby Wiener that Mr Carswell "could have said sorry, but he hasn't got the guts to do it".
Douglas Carswell has denied suggestions he stabbed David Cameron in the back by defecting to Ukip.
He told ITV News' Libby Wiener he had nothing against "nice guy" David Cameron, but had to leave the Conservatives because the Prime Minister was "not serious about change".
He questioned what the difference would be if Ed Miliband's "gang replaced the current gang" in Number 10.
George Osborne has labelled the defection of Douglas Carswell to Ukip as "regrettable and counter-productive".
Speaking in Brighton today, the Chancellor said that the best way to secure a referendum on Britain's membership of the European Union was to have a Conservative government after the next election.
"That's the choice people are going to face, whether it's at the by-election in Clacton or at the general election next year," Mr Osborne said.
Nigel Farage, the Ukip leader, and the party's new candidate for Clacton have been campaigning on the streets of the seaside town this morning.
Douglas Carswell will contest the seat for the eurosceptic party after defecting from the Conservatives yesterday, triggering a by-election for the constituency.