The Liberal Democrats have come under fire for encouraging children to canvass for them in the local elections by offering them sweets.
Sir Menzies Campbell is leading the Lib Dem campaign
A Lib Dem election guide advises candidates to act like the "Pied Piper" by handing out toffees and leaflets.
The Tories said it was "irresponsible" and would entice children to accept sweets from strangers.
But the Lib Dems defended the leaflet saying the Tories' claims were a "rehash of absurd allegations".
Lib Dem chief executive Chris Rennard said: "All political parties find that young people are often willing deliverers of party literature."
A Lib Dem spokesman later added: "Rather than launching negative attacks on our opponents, Liberal Democrats will be campaigning during these elections on the issues that matter to local people, such as the environment, Council Tax, crime and anti-social behaviour."
The Lib Dems' official local election guide advises candidates to recruit children from council estates.
Spelling out the details it says: "You go into the middle of a council estate with your leaflets and you shout at all the local kids you can see and hear 'any of you lot want to help deliver all these leaflets?'.
"Then proceed Pied Piper-like round the estate doling out badges and toffees and leaflets, the last at least to be pushed through doors by the shouting, squealing and quarrelsome horde."
Tory deputy chairman Eric Pickles demanded the Lib Dems withdraw the advice.
He said: "Political parties have to be responsible and not encourage children to get in potentially dangerous situations.
"No responsible adult should ever entice unsupervised children to take sweets from strangers. This election manual is completely oblivious to common sense.
"At a time of heightened concern about the safety of children, I do not believe that the public will tolerate such reckless electioneering by the Liberal Democrats."
The Lib Dems have come under fire before for advice offered to election candidates.
In 2003, the Conservatives reported the party to the parliamentary standards watchdog for producing a "disreputable" campaign guide.
The Tories claimed the guide, which advised candidates to "be wicked, act shamelessly, stir endlessly" and says positive campaigning will not be enough to win control of the council" brought local government into disrepute.
Mr Pickles said the publication was still for sale on a Lib Dem website, despite being condemned by Lord Rennard, and he called for it to be withdrawn.