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LONDON, April 13 (Reuters) - The Scottish National Party has nearly doubled its lead over Britain's opposition Labour Party to 28 percentage points in the last month ahead of a close-fought election on May 7, according to an opinion poll published on Monday.
The TNS poll showed the SNP was on course to win 52 percent of the vote in Scotland, up 6 percentage points on last month, while support for Labour fell 6 points to 24 percent.
What happens in Scotland is crucial because if Labour does poorly in what has traditionally been a stronghold, its chances of ousting Prime Minister David Cameron's Conservatives and of winning outright will be undermined.
With neither Labour nor the Conservatives expected to win an overall majority, Scottish nationalists hope to find themselves in a kingmaker position less than seven months after losing a referendum on independence.
A spokesman for TNS, which polled 978 adults between March 18 and April 8, said this was the highest level of support it had recorded for the SNP in recent years.
It follows a separate survey by YouGov last week which gave the SNP its biggest ever lead, showing the nationalists could win nearly all of Britain's 59 parliamentary seats in Scotland. (Reporting by Kylie MacLellan; Editing by Andrew Osborn)