The Sun has today given its backing to the Conservative Party and warned its readers that a vote for UKIP would bring "a Labour/SNP nightmare closer by eroding Tory chances".
But the title's Scottish edition has given its endorsement to the SNP, saying leader Nicola Sturgeon would "fight harder for Scotland's interests at Westminster, offering a new hope for our country".
On the the divergence of views between the two editions, a Sun spokesman said: "The Sun is written first and foremost for its readers, and the UK edition and Scottish edition have two very distinct audiences.
"If Scotland and England were playing each other at football, no one would expect The Scottish Sun to support the English national team."
The Sun is the UK's biggest selling newspaper, recording an average circulation of 1,858,067 in March, according to ABC figures. In Scotland, the title's circulation last month was 224,298, making it the biggest newspaper in the nation. The Daily Record has a total UK ciruclation of 200,127, and 190,985 in Scotland.
The Sun's front page today, coming shortly before a royal birth is expected, had the headline "It's a Tory" and featured a picture of David Cameron's face on a baby being cradled by the Duchess of Cambridge.
The newspaper said that only his party could keep the economy on track, "stop the SNP running the country" and guarantee an EU referendum.
It levelled some criticism at the PM and his party for being "too aloof" and failing to raise wages sufficiently – but it said spending cuts had been "essential" to turn the economy into "the envy of the Western world".
In a dig at Labour leader Ed Miliband's interview with the comedian-turned-activist, it said: "Conspiracy theorists like Russell Brand, the 39-year-old teenager, believe The Sun backs the Tories because we are all part of some evil elite behind every bad thing ever.
"Here's the real reason: because this time they are by far the best bet for the prosperity and happiness of millions of ordinary people who read The Sun. It really is that simple."
The Scottish Sun went with a Star Wars motif, with Sturgeon mocked up as a light sabre-wielding Princess Leia under the headline "Stur Wars".
It was speculated before the Scottish independence referendum last year that The Scottish Sun could back the Yes vote. Former SNP leader Alex Salmond is reported to have a close relationship with News Corp chairman Rupert Murdoch – who owns The Sun titles. Last year, Salmond described Murdoch as a "remarkable man" in a GQ interview (Telegraph report). At the Leveson Inquiry, it emerged that Salmond had met five times with Murdoch since 2007, and twice with his son, James Murdoch.
This week, the first page inside Private Eye accused Sturgeon of "reluctance to cross Rupert Murdoch". It said: "Sturgeon shows no sign of undoing the tireless work of her predecessor Alex Salmond in developing close ties with the Digger. And with the Scottish edition of the Sun doing everything it can to talk up Sturgeon (so desperate is the Digger to see Labour fail), why indeed bite the hand that is feeding her?"
The Labour, Liberal Democrat and Green Party manifestos each made commitments to media "plurality".
The Labour manifesto said: "No one media owner should be able to exert undue influence on public opinion and policy makers. No media company should have so much power that those who run it believe themselves above the rule of law." This is an apparent reference to the phone-hacking scandal.
Last week, The Independent reported that Murdoch told Sun journalists in February to get the paper's "act together" and do more to stop Labour winning the election.
The Sun has responded to the report by saying that its political coverage is informed by how Labour policies affect its readers.
The News Corp chairman – who owns The Sun, The Times and The Sunday Times – visited London at the end of February, and reportedly warned journalists on his tabloid newspaper of the threat a Labour government would have on the company.
Last week, in an editorial, The Sun said Labour's decision to take on media ownership issues was a "direct result" of its opposition to the party.
In June 2013, Labour deputy leader and shadow culture secretary Harriet Harman said that the party did not address media ‘plurality’ in 1997 for fear of losing the election. But she said: “We’re in different times now.”