Labour campaigners have handed out leaflets to commuters at 70 Tube, rail and bus stations in London, protesting about increases to fares which came into force on Sunday.
The party said average rises of 6.8% would "squeeze the standard of living".
Mayoral candidate Ken Livingstone said there had been a 44% rise in bus fares since Boris Johnson took office in 2008 and told him to "get a grip" on prices.
Mr Johnson has said the increases were kept to an "absolute minimum".
Mr Livingstone, who served as mayor from 2000 to 2008, said: "The reality of life under the Conservatives is VAT up and fares up, whilst the Tory mayor of London defends bankers' bonuses and presses for the richest to pay less tax.
"The increases in fares for outer London and the poor performance of many services show that the mayor does not speak up for the suburbs."
He called this week's price rises "unfair and unnecessary".
Campaign groups such as London TravelWatch have criticised the withdrawal of Travelcards serving zones 2 to 6, which avoid central London, as well as the daily passes for zones 1 to 3 and 1 to 5.
Jubilee Line services are currently severely delayed due to a broken down train and the Piccadilly Line is facing major disruption due to earlier signal failures.
Bob Crow, general secretary of the Rail, Maritime and Transport (RMT) union, said London commuters had been faced with severe delays "while fares shoot up through the roof".
Mr Johnson said last week he had maintained fares at "the absolute minimum while still protecting the vital improvements that London's transport network needs".
"Those improvements include upgrades to the Tube, the delivery of Crossrail, and maintenance of London's bus network," he said.
Free and concessionary travel had been protected, the mayor added.