David Cameron has challenged Ed Miliband to publicly rule out any post-election pact with the SNP, saying a party which wants to “break up Britain” has no place in the country’s government.
The Prime Minister said a Labour administration supported by the SNP’s votes would be the “worst outcome” for the UK.
His comments echo the concerns raised by former prime minister Sir John Major and come as ex-Tory chairman Lord Baker suggested a grand coalition between the Conservatives and Labour may be necessary to curb the influence of the SNP at Westminster if the Scottish nationalists’ opinion poll surge leads to them gaining dozens more MPs.
At a campaign event to mark two months until polling day, Mr Cameron said: “If you thought the worst outcome in this election is a Labour government led by Ed Miliband, think again.
“You could end up with a Labour government led by Ed Miliband, propped up by Alex Salmond and the Scottish National Party.
“You could end up with an alliance between the people who want to bankrupt Britain and the people who want to break up Britain.
“Even today, Ed Miliband will not rule out a deal or backing from the SNP.
“If he cares about this country, he should do so. You cannot let the people who want to break up our country into the government of our country.”
At a campaign event in Labour-held Harrow West in north London, Mr Cameron accused Mr Miliband’s party of being “placard-waving hypocrites” and said the electorate had to decide who they wanted in charge in a “dangerous” and “insecure” world.
Despite the surge in support enjoyed by minor parties, Mr Cameron stressed that the choice facing the public was whether he continued in Number 10 or if Mr Miliband took up residence in Downing Street.
He said: “This election is a choice. And yes, there will be a lot of names on that ballot paper – you can vote Green, you can vote Ukip, you can vote Plaid Cymru, you can vote SNP, you can vote Lib Dem.
“But there are only two choices – there’s the Conservatives or Labour. There’s only two people who can end up as prime minister – me or Ed Miliband.
“We have got to be very clear about this choice.
Highlighting the global threats facing the UK, he said: “We live in a dangerous and insecure and difficult world.”
He continued: “When I think of the dangers that we face, with all that Russia is doing in the Ukraine, I know that we are in safe hands.
“When I think of the dangers of extremist Islamist terrorist violence, not just the other side of the world but here on our streets, I know that Britain is in safe hands.
“When I see the insecurity there is, the dangers of a Greek exit from the euro that would knock everybody sideways, I know we are in safe hands.”
“But at the election the country will be in the hands of the people.
“Who do you want making those decisions, who do you want fighting for a better deal in Europe – me or Ed Miliband?
“Who do you want standing up to Russian aggression and making sure we safeguard our continent, me or Ed Miliband?
“Who do you want making sure we take the right decisions, the tough decisions, to fight terrorism, to fight Islamist extremism to try to create a safer world and safer country?
“Who do you want making those decisions?”
Mr Cameron, casually dressed in a sweater and open-necked shirt, told supporters that Labour had claimed to be “the party of the young, the party of the NHS, the party of the many”.
He said: “The party of the young? These are the people who saw youth unemployment double, who left people on the scrapheap because they didn’t have the guts to reform our welfare system and help get people out to work.
“The party of the NHS? These are the people of the Mid Staffs health disaster, where people were left begging for a glass of water, lying in their filth, drinking out of vases.
“That is the Labour Party.
“The party of the many? These are the people who saw the number of children growing up in households where no-one worked double.”
Mr Cameron said the Tories faced “another enemy” at the election – voter apathy.
“Let’s push away that idea that voting doesn’t matter, it never changes anything and no-one believes in anything. We have changed our country for the better and with another five years we can change it still more.”