Mr Johnson say Labour will protect front line policing
Home Secretary Alan Johnson has called on the Mayor of London to guarantee police safer neighbourhood teams are protected from cuts.
Boris Johnson has previously said it is impossible to guarantee any team will be protected from budget shortages.
Alan Johnson said: "Labour will ensure frontline policing is protected but the Conservatives won't match this."
The Conservatives said it was "ludicrous" to suggest they would put policing at risk.
Safer neighbourhoods teams - typically comprising a sergeant, three constables and three PCSOs - were rolled out to every ward in London in 2004.
The idea was for the teams to boost community policing and identify local troublemakers.
During a visit to Hammersmith, Alan Johnson asked the Conservatives to guarantee they would not cut the teams.
He said: "The Conservative threat to frontline services is shown here in London where the future of safer neighbourhood police teams is at risk from the Conservative mayor Boris Johnson.
"We are issuing a challenge to every Tory candidate in the capital today to say where they stand on Boris Johnson's failure to protect the safer neighbourhood police team guarantee."
A spokeswoman for the mayor said the safer neighbourhood teams have helped cut crime across London since May 2008.
She said: "However, tackling crime in a city as diverse as London is a huge task and policing flexibility is a must if we want to continue to make the city safer.
"Under Boris Johnson, the Met has a record number of warranted officers and as the mayor has already stated he is committed to increasing it yet further."
The Conservative Shadow Home Secretary, Chris Grayling, said: "It's just ludicrous to suggest that the Conservatives would put local policing at risk - it's at the very root of our approach.
"We want to free up the police to spend more time on the beat. And we want to encourage proper neighbourhood policing so people feel safe again."
He added: "What we won't do is dictate from Whitehall how local police forces should do every aspect of their job."
A squeeze on public spending has meant the Metropolitan Police have already been forced to implement a recruitment freeze.
Some 2,000 recruits have been told they must wait indefinitely before starting their roles.
Liberal Democrat crime spokesman Chris Huhne said: "Boris Johnson's cuts in police officers and neighbourhood policing is a warning of what would happen under a Conservative government.
"The Tories won't even commit to protecting police numbers. The Liberal Democrats are the only party pledging 3,000 more police on the street, including more than 600 in London."