House of Commons speaker Sir Lindsay Hoyle has led protests against the temporary closure of an A&E department amid the coronavirus crisis.
Chorley and South Ribble Hospital's troubled emergency department has been downgraded to an urgent care centre.
Lancashire Teaching Hospitals Trust said it was part of plans to "save lives" and patients would be treated at Royal Preston Hospital.
Chorley MP Sir Lindsay said it was not time "to reduce emergency provision".
The trust said a number of temporary changes to services would increase the number of critical care beds available in central Lancashire by 400% and was "essential to saving lives", according to the Local Democracy Reporting Service.
Sending patients with respiratory complaints to the Royal Preston meant it would be able to "safely separate" suspected cases of coronavirus from those being treated for other conditions.
In a tweet, Sir Lindsay said he "wasn't surprised" calls for a rethink of the plans had been ignored.
"All of the MPs have come out against this, but we have no influence. Even the Health Secretary has been involved, but they are refusing to do anything other than close the department," he said.
"The urgent care centre won't have the specialists to make the [necessary] decisions, so you'll just end up pushing people to other A&Es.
"I think the Secretary of State should step in and bring in new management at the trust," Sir Lindsay added.
South Ribble MP Katherine Fletcher said: "All of the local MPs and both local councils have come out against this.
"The trust have communicated appallingly throughout and I will be holding them to account on their promise that this change is temporary," she said.
The trust said a provisional date for services to return had not been set but that a "de-escalation plan will be prepared".
Last year a report by two clinical commissioning groups concluded it would not be "clinically viable" to retain the hospital's A&E department.
The unit has been operating on a part-time basis for three years and spent much of 2016 completely closed.