Murco has denied rumours the refinery will close and says it is working with a potential buyer who wants to run the site as a business.
Opponents say that offshore power and Wylfa Newydd's power could instead be piped under the sea - the most costly option.
With exactly half the seats in the Assembly, Labour needs at least one of the other parties to support its budget or abstain.
Local Assembly Member, Rosemary Butler, has described the closure of Avana bakery as "absolutely devastating".
Having spoken to senior management I understand it will be a phased closure with no jobs being lost in the immediate future. However, the losses are due to start towards the summer of 2014.
This is a sad day for the loyal workforce and for Newport as a whole. The business has been an integral part of the local community for many years and I am disappointed that Avana was unable to secure a new contract to safeguard its future. Avana has confirmed that it will continue to fight to secure new contracts.
– Rosemary Butler AM, Labour, Newport West
I will contact the Minister to ensure all possible advice and support will be available from the Welsh Government for those affected.”
A Newport bakery which employs 650 workers will close.
Avana Bakeries first announced that jobs were at risk in February, after the loss of a major cake contract.
Company bosses said their priorities is to minimise the number of redundancies by looking to redeploy staff to other areas.
In a statement, the company said: "We will now work with all our colleagues and our customers to implement a phased closure, which we anticipate will end by summer."
Unions and politicians have continued to meet today at the Murco oil refinery in Milford Haven in an attempt to secure its future and save 400 jobs.
All eyes are on West Wales, with First Minister Carwyn Jones visiting Murco on Monday and the Welsh Secretary due to host a jobs summit in the region.
Following Murco's announcement yesterday that it was going into a period of consultation, the community around the plant says it fears for the economic future of the whole area.
Preseli Pembrokeshire MP Stephen Crabb is visiting the Murco oil refinery in Milford Haven to meet with staff and management over the plant's future.
– Stephen Crabb MP
Yesterday I had discussions with various UK and overseas companies who are very interested in the sale of the Murco site.
There is widespread acknowledgment that the Milford Haven oil refinery is a very good facility and that there is a future for the plant if global trading conditions improve.
Investor interest has not gone away and I believe it is still all to play for in this deal.
I want Murphy to explore every possible avenue in order to keep that refinery operational.
Around 400 jobs are at risk after Murco announced yesterday it would be entering into a period of consultation with employees.
Around four hundred jobs are at risk at the Murco oil refinery in Milford Haven after a potential deal to buy it collapsed.
The firm's parent company Murphy Oil Corporation is understood to have been in talks with with a number of companies for more than three years in a bid to find a buyer. But today Murco announced it will be entering into a period of consultation with workers.
Our West Wales correspondent Kevin Ashford has been following this story.
The union Unite has called on the UK government to step in and save the Murco oil refinery in Milford Haven, which is at risk of closure after a potential sale fell through.
– Andy Richards, Unite Welsh Secretary
The UK government cannot repeat the mistake of Coryton and allow another of the UK’s oil refineries to close. It needs to do everything possible to maintain refining capacity at Milford Haven to meet the nation’s energy needs and save hundreds of jobs at the site.
The workforce has been under real pressure and worked hard in a climate of uncertainty over the past four years, while the American owner looked for a new buyer.
They have done nothing to deserve this treatment. It‘s now time for all parties that have a stake in the future of Milford Haven to fight tooth and nail to save the refinery.
The UK and Welsh governments have both spoken of their determination to work together with Murco to safeguard the future of the plant.
Pembrokeshire County Council has said it hold hopes for a "viable, sustainable purchaser to come forward who could guarantee the future of oil refining" at the Murco site in Milford Haven.
Council leader Jamie Adams said it will continue to work with the Welsh Government to offer more support.
– Cllr Jamie Adams, Pembrokeshire County Council leader
I am sorry to hear that the sale of the refinery has fallen through.
We hope that it will continue to operate as a refinery as that will save the jobs of both refinery staff and of the many local sub-contractors who work there.
The County Council and the Welsh Government will continue to support Murco as they look for an alternative buyer.
Ideally we would want a viable, sustainable purchaser to come forward from within the industry who could guarantee the future of oil refining at the site.
The Welsh Government has said it is "very disappointed" by the news that a deal over the potential sale of the Murco oil refinery has fallen through, putting hundreds of jobs at risk.
Economy Minister Edwina Hart said the Welsh Government would continue to work closely with UK ministers, and bosses at Murco, and "the First Minister will be visiting the site at the earliest opportunity to explore all possible options to retain these valuable jobs at Milford Haven."
We are very disappointed by this announcement and fully recognise the impact this will have on the employees, contractors and businesses in the area. We have been working very closely with Murco over the past four years to try and secure the ongoing operation of the refinery and protect the jobs at the Milford Haven site.
We have spoken to the senior management at Murco this morning to offer our ongoing support. The First Minister will be visiting the site at the earliest opportunity to explore all possible options to retain these valuable jobs at Milford Haven.
– Edwina Hart, Economy Minister
We are very keen to work collaboratively with all levels of government and I have already spoken with the UK Minister for Business and Energy to discuss how we can support the employees and the company through this difficult and worrying time.
Welsh Secretary David Jones has said the UK government "very much regrets" hearing that a deal to sell the Murco oil refinery in Pembrokeshire has fallen through.
He said: "We stand ready to support Murco, with a view to securing the future of the plant, and the jobs of the people who work directly and indirectly for it."
– David Jones, Welsh Secretary
The Government very much regrets to hear the developments at the Murco Petroleum refinery in Milford Haven, and the potential impact this may have on its employees, their families and the community.
The Wales Office is in close contact with colleagues at the Department of Energy & Climate Change, the Welsh Government and with officials at Murco Petroleum Ltd on this matter.
We stand ready to support Murco in their ongoing efforts to find a buyer, with a view to securing the future of the plant, and the jobs of the people who work directly and indirectly for it.
Murco says it has spent three years trying to find a buyer for its oil refinery at Milford Haven, amid "a particularly challenging market, caused by declining demand and increased international competition."
The company announced it is today entering a period of consultation with workers, including those who work at the Pembrokeshire plant, and acknowledges this "will understandably be an unsettling time for everyone concerned."
– Tom McKinlay, Managing Director of Murco
Our focus today is on helping our people understand what this means for them.
For over three years, we have left no stone unturned in trying to find a buyer for the plant.
Our efforts highlight the challenges and on-going changes confronting the European refining industry and are in no way a reflection on the attitude and work ethic of the Murco team.
We will continue to do all we can to ensure our employees are supported during this time.
Murco is a subsidiary of the Murphy Oil Corporation, an American company.