The Tories' apparent shift in popularity has come on the back of a Conservative campaign styling themselves as the party to preserve the United Kingdom union amidst SNP plans for a second independence referendum.
The party's leader at Westminster, Angus Robertson MP, said: "When Theresa May comes to Scotland, she needs to tell pensioners they will get what is rightfully theirs".
Sturgeon replied: "The simple point that I am making is this: GERS does not tell us anything much about the finances of an independent Scotland".
Gavin Newlands MP highlighted the SNP Scottish government's strong record for pensioners - including protecting and investing in Free Personal and Nursing Care for the elderly, protecting Winter Fuel Payments and working with Age Scotland to increase the uptake of financial support available to older people.
Labour and the Lib Dems said the SNP was failing to make improvements.
The Scottish Conservative candidate for Edinburgh South West, Miles Briggs, said that Labour was hoping to "sell pro-UK Scots down the river" by doing a deal with the SNP after the election.
But Mr Rennie accused the SNP in government of having treated the north-east of Scotland "like a cash cow", adding: "Nicola Sturgeon can not escape the fact that the SNP's actions have directly left areas like Aberdeen short changed".
Like Lord Darling, Mr Murray is also a past critic of Mr Corbyn, and resigned as shadow Scottish Secretary previous year.More news: Looking at the Technicals for Dr Pepper Snapple Group, Inc. (NYSE:DPS)
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"We see it from the Liberal Democrats and we see it from Nicola Sturgeon's Scottish National Party".
"The Tories found the money to cut taxes for the rich in their budget, but seem unwilling to find the money to give state pensioners a decent income - no government which believes in a fair society could pursue those two positions".
"This election is a chance to change the direction of our country and put an end to the SNP's obsession with independence".
He added: "I've always thought Theresa May's main problem in the House of Commons is not actually the Remainers, they are the Brexiteers, who disposed of three other leaders of the Tory party within recent memory, and I'm sure she's very conscious of the fact that left to their own devices they might do the same again".
Commenting on the interview, Scottish Labour's general election campaign manager, James Kelly, said: "Alex Salmond's car-crash interview exposed the reality of the SNP's record in government".
Scottish Liberal Democrat leader Willie Rennie said: "Sticking his fingers in his ears and shouting "la-la-la" will not change the truth of Alex Salmond's government's educational performance".
That was a reference to a quote from a now infamous 1970 Scotland Office memo about joining the EEC that was released in 2000. It wasn't the result I wanted but democracy means that that is where we are.
The Scottish Greens' education spokesman, Ross Greer, said his party was willing to "work constructively" with the Scottish government to raise standards in education.