Chancellor Alistair Darling says the Conservatives and Liberal Democrats must decide on Monday whether or not they will form a government together.
The two parties are set to enter their third day of talks about a potential power-sharing agreement after Friday’s inconclusive election result.
"I just think there comes a point where you have to decide if there is a deal or no deal," Mr Darling told the BBC.
The public and markets wanted to see a "government in place", he added.
Negotiating teams from the Tories and Lib Dems are set to meet for the third successive day as the two sides discuss possible arrangements to put together a government.
Lib Dem leader Nick Clegg met his Conservative counterpart David Cameron twice over the weekend but also held a meeting with Prime Minister Gordon Brown, who has said he is ready to discuss a possible deal of his own with the Lib Dems should the talks break down.
Mr Darling, who remains as chancellor for the time being, said he believed the Tory-Lib Dem talks could not continue for ever.
"I don’t think it would do any good to let this process drag on," he told Today.
"I hope by the end of today they will decide whether they can do a deal or not. I am not saying that tomorrow’s the end of the world but I just make the general observation that there does come a point in any negotiations – either you can do a deal or you can’t.
He added: "If there’s not a deal, no doubt they will talk to us. The key thing everybody would expect, whether you’re a market or more importantly in some ways from the point of view of people at home, we want to see a government in place."
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