The RMT union has come under fire as London braces for Tube strikes over four days this week.
With Londoners facing widespread travel disruption, ministers and Sir Sadiq Khan were urged to end the union’s “stranglehold” on the capital and stop it “calling the shots”.
But there were no signs that the industrial action by the RMT was due to be called off.
The Standard understands that there are currently no meetings scheduled to take place between Transport for London and union officials to try to reach an eleventh-hour deal.
So, Underground drivers belonging to the RMT union are set to walk out from midday on Tuesday (April 21) for 24 hours, and again from midday on Thursday (April 23) for 24 hours.
The timings mean the industrial action by the National Union of Rail, Maritime and Transport Workers (RMT) will cause travel misery for Londoners over at least four days.
Most lines will see a reduced service but the Piccadilly and Circle lines are expected to be shut down.
There will also be no services on the Metropolitan line between Baker Street and Aldgate, or on the Central line between White City and Aldgate.
Shadow Transport Secretary Richard Holden told The Standard: “Sir Sadiq Khan promised zero strikes, but London is being crippled while the militant backers of Labour MPs, the RMT, call the shots.”
Mr Holden added: "Conservatives warned this would happen.
“Yet Labour still won’t stand up to their union paymasters as passengers and taxpayers deal with the fallout.”
The dispute is over the introduction of a four-day working week, which the RMT says could increase fatigue and compromise safety.
Transport for London denied the claims, emphasising that the changes are voluntary and criticised the walkouts as “completely unnecessary.”
Unlike the RMT, members of the Aslef train drivers' union voted to accept the proposals.
One of its London Underground organisers said it was “exactly the sort of deal every trade union should be trying to achieve”.
The Liberal Democrats warned that the walkouts would hit high streets in the city, the West End and wider tourism sector and economic growth.
Luke Taylor, the party’s London spokesman and MP for Sutton and Cheam, said: “These Tube strikes will cause huge frustration for commuters trying to get to work and tourists looking to explore our incredible city, just as drivers are being hit by price increases at the petrol pump.”
The industrial action, which is expected to cost the capital £210 million according to one estimate, has been condemned by business chiefs.
Laila Cunningham, Reform UK's candidate for Mayor of London, called for more automation on the Tube to cut costs, reduce disruption and stop strikes.
Criticising Sir Sadiq, she said: “His weak leadership has let militant unions hold our city hostage with endless strikes, costing the city and businesses hundreds of millions of pounds and grinding London to a halt.
"The TfL unions' stranglehold on our transport has to end.”
A City Hall source said: “Nobody wants to see strike action which has a serious impact on Londoners, businesses and commuters.
“The Mayor continues to urge the RMT and TfL to get around the table to resolve this matter and call off this planned strike action.”
Zack Polanski’s Green Party, though, sided with the RMT strikers.
Caroline Russell, leader of the Greens on the London Assembly, said: “The drivers are raising really important issues about their working conditions that ultimately affect safety.
“What’s important is that TfL listens and engages with the striking drivers so that their issues can be addressed through dialogue.“
The RMT said it had approached negotiations with TfL in “good faith”.
The union’s general secretary Eddie Dempsey added: “But despite our best efforts, TfL seem unwilling to make any concessions in a bid to avert strike action.”
Claire Mann, TfL's chief operating officer, stressed that the reforms would allow it to offer train drivers an additional day off, while at the same time bringing the Tube in line with working patterns of other train operating companies, “improving reliability and flexibility at no additional cost”.
People planning to use the Underground on strike days were urged to “check before they travel” due to the expected level of disruption and other TfL services, such as the Elizabeth line, London Overground, buses and London trams, “likely to be very busy”.
