Tony Blair has defended his wife Cherie after she was accused of "cashing-in" on her position with a lucrative speaking engagement in the US.
Cherie is offering an inside account of the "First Lady of Downing Street"
The Conservatives urged Mrs Blair to hand her £30,000 fee for the lecture on life inside Downing Street to charity.
Asked about the row, an exasperated Mr Blair said: "I don't think there's ever anything I can say on these things that can make it better."
He said Cherie had also helped back London's Olympics bid while in the US.
Mr Blair was in Washington for talks with George Bush before the G8 summit.
Mrs Blair said the fact her speech came at the same time her husband was in the US was a coincidence.
She said she had to "walk a tightrope" with her joint roles as a professional woman and as the UK prime minister's wife.
She told a US interviewer her engagement had been booked well in advance, adding: "It has crossed my mind that of all the 365 days in the year that Tony could have come, this was not my favourite."
She went on to say "you can't please all the people all the time".
Mrs Blair argued that Dennis Thatcher had a number of "outside interests" and "no-one found anything wrong with that".
The row centres on Mrs Blair's decision to give a talk on Tuesday at Washington's Kennedy Centre - billed as the inside account of the "First Lady of Downing Street".
The Conservatives say the lecture went against the spirit of the ministerial code which prevents members of the government making money from commercial activities relating to their job.
Shadow Commons leader Chris Grayling says the code should cover activities directly linked to the job of the Prime Minister.
Mr Grayling said Mrs Blair should donate any fee to charity arguing the "commercial nature" of her trip was "inappropriate".
He said: "What is wrong to me is the Blair family making tens of thousands of pounds out of effectively exploiting Mr Blair's job when the ministerial code says they are not allowed to do that."
And he has written to Foreign Secretary Jack Straw saying he is "astonished" Britain's ambassador was involved in Mrs Blair's private engagement, after Sir David Manning introduced Mrs Blair at the Kennedy Centre.
"I should be grateful if you could investigate what has happened and in particular why a senior civil servant would agree to participate in a purely commercial event on behalf of Mrs Blair," he writes.
But Downing Street said it was "normal procedure" for Sir David to introduce or accompany "any prominent British citizen visiting Washington".
The Foreign Office said Sir David had introduced TV chef Nigella Lawson and artist Andrew Goldsworthy when they were in Washington.
The spokesman added that on the day of Mrs Blair's speech the ambassador also introduced the headteacher of the local British school in Washington.
A spokesman for London 2012 said: "Cherie Blair, as a senior bid ambassador, has undertaken a series of briefings with the international media and we were delighted that she was able to meet and brief senior figures from the American media while in New York."