Britain's main opposition Labour party on Tuesday sought to pile pressure on the ruling Conservatives over state-run healthcare in a bid to exploit a government weakness and divert attention from its message on Brexit.
Opinion polls show Johnson's Conservatives enjoying a comfortable lead before an election that Prime Minister Boris Johnson has called the "most important in a generation".
Johnson's minority government hopes to secure a parliamentary majority on Thursday to help him pull Britain out of the European Union by the end of next month.
But a ruling party memo published by the pro-Conservative Daily Telegraph newspaper warned that just 40,000 votes in 12 constituencies could see Labour leader Jeremy Corbyn becoming prime minister.
The veteran socialist is trying to stage a late surge by focusing on Tory funding of the taxpayer-funded National Health Service (NHS) since the party came to power nine years ago.
Labour claims nearly 4,700 deaths recorded between October 2018 and November 2019 could be attributed to "patient safety incidents" that resulted from NHS staffing constraints.
"The NHS has to be properly funded and at the moment it isn't," said Corbyn, who has warned that the Tories want to sell off the NHS to private firms, threatening its key principle of free treatment for all.
"All research shows there's a very large number of hospitals where patients are at risk because of staff shortages, because of a lack of equipment, because of poor maintenance of hospital buildings," he told BBC television. "It is a serious issue."
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