Hospital changes: Labour minister joins Royal Glamorgan campaign
Welsh Education Minister Leighton Andrews has joined a campaign to keep key specialist care at Llantrisant's Royal Glamorgan hospital.
Health officials say concentrating services, including the most serious accident and emergency cases, elsewhere offers the "best fit".
Options involving the Royal Glamorgan are also being considered.
Plaid Cymru and Conservatives attacked the plans, Lib Dems said the public were not convinced change was needed.
Mr Andrews said the changes would mean more congestion at other hospitals.
"Safer and more reliable services have to be the priority but if accident and emergency services disappeared from the Royal Glamorgan hospital then most Rhondda people would have to travel to Cardiff, which would overburden services there and lead to greater congestion around the University of Wales hospital (UHW) at the Heath," added Mr Andrews, the AM for Rhondda.
Pontypridd AM Mick Antoniw, Shadow Welsh Secretary Owen Smith and Rhondda MP Chris Bryant also joined the campaign.
Welsh Conservative leader Andrew RT Davies accused the Labour politicians of "blind hypocrisy".
"These are the same politicians who day in day out defend their colleagues in the Labour Welsh government who have starved the Welsh NHS of over £800m in the last 5 years," he said.
"Ultimately these downgrades are the result of a failure to prioritise investment in the NHS budget and an inability to attract clinicians to staff specialist services in the region."
Plaid Cymru leader Leanne Wood also criticised the plans to remove services from Llantrisant.
"The people of Rhondda Cynon Taf (RCT) will be very concerned to discover that critical services could be taken from the Royal Glamorgan hospital in Llantrisant, including from its A&E department, which is the preferred option of hospital chiefs," she said.
She condemned the proposals as "an admission of the Welsh government's failure to deliver these services".
"RCT is an area where many of the residents have chronic health problems, the road network is poor and the local ambulance service has the worst performance in Wales for responding to life-threatening emergency calls.
"People will be rightly concerned that the health boards' preferred option would involve people from RCT travelling further in life-threatening emergencies."
South Wales West Liberal Democrat AM Peter Black cautiously welcomed the proposals.
But he warned that over the consultation period "many representations will be made, particularly from those keen to reverse the decision to downgrade the Royal Glamorgan.
"The final decision is not due to be made until October.
"We need therefore to remain vigilant, continue to make the case for our hospitals to keep these services locally and above all, ensure that the new consultation reflects the views of residents in Swansea, Neath Port Talbot and Bridgend."
However, Welsh Lib Dem leader Kirsty Williams accused the Welsh government of failing to convince the public that change was needed.
"Change in the NHS is some of the most difficult things to manage but it can be done if you have an open an honest dialogue," she said.
"The Welsh government have singularly failed to convince the public and that can be seen by the strong reaction in north Wales and mid and west Wales."
Despite the concerns, Health Minister Mark Drakeford insisted there was a growing acceptance of why the NHS needed to change.
During heated exchanges in the Senedd, he came under fire from opposition AMs.
"As far as the future of health services in Wales is concerned, there is no choice but change," Mr Drakeford said.
"Change is coming in the NHS in Wales, as it is in every other part of the United Kingdom."