Dominic Raab said he has “no idea” if a Conservative donor was asked to pay for Boris Johnson’s childcare as the Foreign Secretary dismissed the allegation as “tittle-tattle”.

The Cabinet minister mounted a defence of Mr Johnson on Sunday amid signs a string of allegations may be damaging the Tories ahead of this week’s elections.

But he declined to deny a report in the Sunday Times that a second invoice for lavish renovations of the Prime Minister’s Downing Street flat may have been settled by a Tory donor.

Mr Johnson is seeking to focus attention on tackling crime and the coronavirus recovery in a pitch to voters before polls open across Britain on Thursday.

It came as two new polls suggested the Conservatives’ lead over Labour has been cut ahead of Thursday’s local elections in England and votes for the parliaments in Scotland and Wales.

The polls will raise concerns among Conservatives that recent “sleaze” allegations battering the Prime Minister are beginning to turn some voters off.

The Electoral Commission this week launched an investigation into whether any donations or loans to pay for the refurbishment of his Downing Street flat were properly declared.

And Mr Johnson has been forced to deny saying he would rather see “bodies pile high” than impose a third coronavirus lockdown, on top of a lobbying row and allegations of cronyism.

But further allegations emerged over how renovations at his No 11 residence were initially paid for and that an MP has received a complaint from a Tory donor that they were asked to pay for a nanny for Mr Johnson’s one-year-old son Wilfred.

The donor was alleged to have said: “I don’t mind paying for leaflets but I resent being asked to pay to literally wipe the Prime Minister’s baby’s bottom.”

A No 10 spokeswoman said: “The Prime Minister has covered the cost of all childcare.”

But she did not respond when asked if Mr Johnson paid for the original bill himself or had reimbursed somebody else.

Asked about the allegation in the Sunday Times, Mr Raab told Sky’s Sophy Ridge on Sunday: “I have no idea, you don’t have conversations like that with the PM. I can’t comment on every little bit of gossip that’s in the newspapers.

“The last thing you asked me about I think is an example of tittle-tattle.”

He declined to deny another allegation that a second invoice for the renovations reported to cost up to £200,000 was settled by a third party directly with the supplier.

“There are three reviews now I think into this and I think the right thing for me to do is not add political commentary that could otherwise prejudice those reviews but to respect the integrity of them,” Mr Raab said.

“So I’m not going to offer you I’m afraid any more commentary or if you like chatter on the various different reports and speculation that I see in the Sunday papers.”

He also said he has “no idea” if Mr Johnson personally called newspaper editors to criticise former aide Dominic Cummings but insisted the Prime Minister is “absolutely focused” on the pandemic.

Meanwhile, the Prime Minister appealed to voters in an article for The Mail on Sunday by saying he would “bring the hammer down hard on the gangs” and set up a “pet theft task force”.

He said the rollout of vaccines, one popular element of his handling of the pandemic, was helping to ease restrictions ahead of the expected relaxations on May 17 and June 21.

“This country is moving forwards cautiously but I hope irreversibly through the steps of the road map,” Mr Johnson wrote.

“Week after week we are seeing how the vaccine rollout is helping to restore our freedoms – and with those freedoms I have absolutely no doubt that our economy will bounce back strongly.”

Although earlier polls suggested the “sleaze” allegations were not significantly denting public support for the Tories, fresh surveys gave evidence to the contrary.

The Conservatives fell to a five-point lead over Labour, with 42% compared to 37%, according to the Opinium poll of more than 2,000 adults between Wednesday and Friday.

That put the Tories down two points and Labour up four compared to a week earlier, halving the Conservatives’ lead ahead of the elections, in which some 48 million people are eligible to vote.

And in separate polling, Focaldata put Labour on 39%, one point behind the Tories, who previously had a healthy lead, according to The Sunday Times.

Mr Johnson has denied breaking any laws over the refurbishment of his No 11 residence and insisted he had paid “personally” for the works.

But he has refused to say whether he received an initial loan from the Conservative Party, as Downing Street launched two separate reviews into the controversy.

Questions intensified when Mr Cummings accused the Prime Minister of wanting donors to “secretly pay” for the works in a “possibly illegal” move.

The elections on Thursday will be the first major electoral test for the Conservatives and Sir Keir Starmer’s Labour Party since the 2019 general election.