The prime minister has been urged to step in and resolve a row involving cleaners at the Houses of Parliament.
Cleaners are demanding £6.70-an-hour
MPs and peers walked past picket lines on Wednesday as up to 140 workers went on strike for a second time.
They are demanding a wage increase from £5.20-per-hour to £6.70, as well as sick pay, a pension, and more holidays.
Labour MP Kate Hoey said: "This could be ended immediately by the prime minister's office saying that this is not acceptable."
"Most MPs thought that this would be sorted out in the summer but it hasn't and I think we will now see more direct support from politicians".
She also complained that £400,000 was being spent building a covered walkway inside Parliament, which MPs had not asked for, when cleaners were being denied decent wages.
Jack Dromey, deputy general secretary of the Transport and General Workers' Union (TGWU), said it was time politicians told the authorities to put more money into the contract.
Mr Dromey also revealed that an offer to increase the pay to £6-an-hour had been made but would involve 30 job losses and a reduction in cleaning standards, which he said was "totally unacceptable".
House of Commons Commission spokesman, Nick Harvey MP, said: "This is a dispute between the contractor and its employees. Over recent months officials have worked hard to find ways of saving money within the contract."
He said the £6-per-hour offer had been made and he understood it was still under negotiation, along with other demands.
The commission has said it would not increase the value of the £2.2m cleaning contract for Parliament.