A fresh row over ballots has flared, with trade unions defending the level of turnouts from workers voting on industrial action and other issues.
Members of the Rail Maritime and Transport union at London Overground are set to strike on Sunday and Monday in a row over jobs, disrupting services.
The union said its members voted by 9-1 for strike action on a turnout of 50%, a mandate that would leave politicians "dancing in the streets".
Conservatives on the Greater London Authority (GLA) said only 43% of staff balloted had voted in favour of strikes.
Transport spokesman Richard Tracey said: "It is absurd that tens of thousands of passengers could face delays and disruption on the London Overground this bank holiday weekend because 43% of train guards - a mere 53 workers - have opted for strike action. Transport for London and the mayor need to begin to think differently about staff strikes to prevent further passenger delays and lost revenues to the London economy."
There have been calls for a threshold of union members taking part, and voting yes, in a ballot before it can be acted on.
Bob Crow, general secretary of the RMT said: "The fact is that the mayor and all the Tory members of the GLA would have to stand down if they applied the same brand of democracy to themselves that these clowns are trying to impose on the unions.
"This policy on one form of democracy for the political class and another for the working class has the whiff of the military junta about it."
Other recent union ballots have also seen big turnouts among Royal Mail workers and managers to oppose privatisation, well above political elections.
Unions pointed out that the average turnout for police commissioner elections was less than 15%, was 34.9% in the 2009 Euro elections, while the percentage of the electorate voting Conservative at the 2010 general election was 36.1%.