Boris Johnson will warn there is a "clear and present" danger of the possibility of another hung parliament if voters do not turn out to vote Conservative on Thursday.
As the general election campaign heads into the final couple of days, Mr Johnson will tell supporters there are "well financed" efforts being made by voters to ensure there is no Conservative majority.
As the prime minister visits Staffordshire on Tuesday, he will say rival parties only need to gain 12 more seats to ensure the possibility that Jeremy Corbyn could be the next incumbent in Downing Street.
“The danger of another hung parliament is clear and present. There are sophisticated and well-financed attempts underway to prevent a Conservative majority through tactical voting,” he will say.
“Jeremy Corbyn and his Lib Dem, nationalist and Green allies need only 12 more seats than last time to make Jeremy Corbyn prime minister and continue the chaos of a hung parliament.
“A vote for any of these parties is a vote for further indecision and two more referendums, on Brexit and Scottish independence. We’ll be stuck in this limbo, this first circle of hell, for the foreseeable future.
“On the other hand, the Conservatives need only nine more seats for a majority. We could finally get Brexit done, end the uncertainty and move on.”
The Lib Dems have insisted they said they would not put Mr Corbyn in No 10 while Labour have said that in the event of a hung parliament they would seek to form a minority government rather than enter into any formal pacts or coalition’s with other parties.
Boris Johnson's chief adviser Dominic Cummings has repeatedly insisted the race to become prime minister is tightening, while a leaked memo seen by the Daily Telegraph the "major risk" for the party was “the belief that the Conservatives are indeed on course to win a comfortable majority”.
The Labour leader, meanwhile, said he was feeling “very happy, very confident” going into the final days of the campaign.
“We’ve got the message out, and we will continue to make sure it gets out over these last few days,” he told The Guardian.
Labour was returning to the offensive on the NHS, warning that under-funding was putting patients at risk.
The party said an analysis it had conducted of more than 120 NHS trust board papers had identified hundreds of risks to patient safety classed as “catastrophic” or “extreme”.