Union leaders are calling on David Cameron to take personal charge of talks to prevent the closure of Tata Steel's Port Talbot plant.
They have accused Business Secretary Sajid Javid of "taking his eye off the ball" and say the PM needs "to get a grip" of the negotiations.
It comes ahead of emergency talks in London between unions and representatives of at risk Tata plants.
The government has said it will offer financial support to help find a buyer.
Tycoon Sanjeev Gupta, founder of commodities firm Liberty House, has had initial talks over a potential purchase of the south Wales plant.
Liberty House said the talks had been "encouraging" and "positive" and described the response of ministers as "pro-active" and "keen to find solutions."
Mr Gupta will return to London on Monday evening to continue the negotiations.
Investment firm Greybull has been in talks with Tata Steel regarding a buy-out of Tata's Scunthorpe operation.
Marc and Nathaniel Meyohas, the brothers behind the firm, are considering a £400m investment in the struggling Lincolnshire plant, potentially saving about 9,000 jobs.
It is understood German group ThyssenKrupp have signalled they are not interested in buying Tata Steel's UK businesses.
Meanwhile, Wales' First Minister Carwyn Jones faces questions from assembly members over the steel crisis later in a hastily reconvened meeting.
Tata Steel announced last week it was selling its loss-making UK businesses and would close its plant at Port Talbot unless a buyer is found.
The company directly employs 15,000 workers in the UK and supports thousands of others, across plants in Port Talbot, Rotherham, Corby and Shotton.
BBC assistant political editor Norman Smith said Liberty House would be unlikely to buy Port Talbot's blast furnace and it was primarily interested in the company's rolling mills and other steel processing plants.
Shop stewards from steelworks across the country are meeting in London to discuss the steel industry crisis later as efforts continue to save thousands of jobs at risk.
The unions wrote to Mr Cameron last week seeking a meeting but say they have so far not received a reply.
Unite assistant general secretary Tony Burke said if the industry was "to be given a fighting chance then the government and Tata need to come clean on their intentions and prior discussions, because so far all we've had is more questions than answers".
He said: "The apparent lack of urgency from Sajid Javid and absence of a clear plan from the government is disturbing for the tens of thousands whose livelihoods hang in the balance and deeply troubling for British Steel's 140,000 pensioners."
Roy Rickhuss, leader of the Community union, added: "By now, no-one underestimates the scale of the challenge we face. We have an entire industry to save and not a lot of time to save it.
"We must also ensure that we hold Tata to a commitment to be a responsible seller and honour its moral and social duties to UK steel communities."
Business minister Anna Soubry is due to visit Rotherham steelworks on Monday.
Speaking to BBC Radio Sheffield, she said the government wanted to find a buyer who would purchase Tata's UK operations "as a whole".
"We need to make sure we get the right deal, obviously that deal is for Tata to decide because they're a private company, but that we do everything we can to make it happen," Ms Soubry said.
Mr Gupta's commodities firm Liberty House has already saved several UK steelworks but BBC political correspondent Carole Walker said he wanted to discuss possible government help on energy costs and to replace Port Talbot's traditional blast furnaces with modern electric arc furnaces.
Mr Javid, under pressure over his handling of the crisis, has signalled that ministers are working on plans to reduce energy costs and take on some of the firm's pension liabilities to make a purchase more attractive to investors.
A source involved with the talks between Liberty House and the government said the company and other potential buyers would regard taking over Tata's pension liabilities as "too big an ask".
Tata Steel has said there is "no fixed timeline" for the sale process but stressed that urgency is needed to avoid "a long period of uncertainty" for employees and customers.
Labour says the government should be prepared to take the Port Talbot plant - which Tata says is losing £1m a day - into public ownership to safeguard its future until a buyer can be found.
The Welsh Assembly has been recalled from its Easter recess to discuss the crisis.
Andrew Davies, leader of the Welsh Conservatives, told BBC Radio 4's Today programme the cost of business rates - which are controlled locally by the Welsh government - had been "a constant thorn in the side of steel works", and called for Welsh ministers to take action.
Welsh Economy Minister Edwina Hart, who is chairing a steel task force, said the Welsh government was willing to look at reducing business rates, but stressed UK-wide rules limited how much they could be varied.
It was up to the UK government to take the lead on "fighting for steel" by stepping in with cash, including investment into plants and machinery, she added.