Dominic Raab, the foreign secretary, has played down the prospect of becoming “the next Portillo” at the election, as polls suggest he risks losing his seat due to tactical voting.

At the 1997 general election, Michael Portillo, then defence secretary, became a high-profile scalp and a symbol of the party’s defeat by Labour when a string of veteran Conservative MPs lost their seats.

Mr Raab’s seat, Esher and Walton in Surrey, voted 58 per cent for Remain in the 2016 EU referendum, while the former Brexit secretary is a vocal Leave supporter.

A Deltapoll survey indicates he now only holds a five-point lead over Monica Harding, his Liberal Democrat opponent.

The Tories have held the seat since 1910 but tactical switching by Labour supporters or a higher turnout among the under-40s could hand the seat to the Lib Dems.

General election: Constituency profiles Show all 28 1 /28 General election: Constituency profiles General election: Constituency profiles Dunbartonshire East Constituency profile: Dunbartonshire East. See story POLITICS Election. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Milton Keynes South Constituency profile: Milton Keynes South. See story POLITICS Election MiltonKeynes. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Great Grimsby Constituency profile: Great Grimsby. See story POLITICS Election Grimsby. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Southampton Itchen Constituency profile: Southampton Itchen. See story POLITICS Election Southampton. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Truro & Falmouth Constituency profile: Truro & Falmouth. See story POLITICS Election Truro. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Brecon & Radnorshire Constituency profile: Brecon & Radnorshire. See story POLITICS Election Brecon. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Dudley North Constituency profile: Dudley North. See story POLITICS Election Dudley. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Norwich North Constituency profile: Norwich North See story POLITICS Election Norwich. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Fife North East Constituency profile: Fife North East. See story POLITICS Election Fife. Infographic PA Graphics Press Association Images General election: Constituency profiles St Ives Constituency profile: St Ives. See story POLITICS Election StIves. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Derbyshire North East Constituency profile: Derbyshire North East See story POLITICS Election Derbyshire. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Stirling Constituency profile: Stirling. See story POLITICS Election Stirling. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Sedgefield Constituency profile: Sedgefield. See story POLITICS Election Sedgefield. Infographic by PA Graphics Press Association Images General election: Constituency profiles St Albans Constituency profile: St Albans. See story POLITICS Election StAlbans. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Blackpool South Constituency profile: Blackpool South. See story POLITICS Election Blackpool. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Cambridge Constituency profile: Cambridge. See story POLITICS Election Cambridge. Infographic by PA Graphics Press Association Images General election: Constituency profiles Finchley & Golders Green Constituency profile: Finchley & Golders Green. See story POLITICS Election Finchley. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Bedford Constituency profile: Bedford. See story POLITICS Election Bedford. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Wells Constituency profile: Wells. See story POLITICS Election Wells. Infographic by PA Graphics PA Graphics Press Association Images General election: Constituency profiles Lancaster and Fleetwood Constituency profile: Lancaster and Fleetwood. See story POLITICS Election Lancaster. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Harlow Costituency profile: Harlow. See story POLITICS Election Harlow. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Hartlepool Constituency profile: Hartlepool. See story POLITICS Election Hartlepool. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Telford Constituency profile: Telford. See story POLITICS Election Telford. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Stockton South Constituency profile: Stockton South. See story POLITICS Election Stockton. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Uxbridge & South Ruislip Constituency profile: Uxbridge & South Ruislip. See story POLITICS Election Uxbridge.Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Ashfield Constituency profile: Ashfield. See story POLITICS Election Ashfield. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles Moray Constituency profile: Moray. See story POLITICS Election Moray. Infographic PA Graphics PA Graphics Press Association Images General election: Constituency profiles South West Hertfordshire Constituency profile: South West Hertfordshire. See story POLITICS Election Tories Gauke. Infographic PA Graphics PA Graphics Press Association Images

When Deltapoll asked how people would vote if they saw it as a contest between the Tories and Lib Dems, the two parties were tied at 48 per cent each, The Observer reported.

Mr Raab, who had a healthy majority of 23,298 at the last election, said he was “not really” worried about losing his seat but acknowledged that “with a seat like mine you never take anything for granted”.

Last month at a local hustings, he was “literally booed by half the room”, according to one constituent, and there was “continued heckling” as he gave his closing speech.

When he said the Tories would deliver a “moderate Brexit” the room erupted in laughter, The New European reported.

He told Sky News’s Sophy Ridge on Sunday: “The polls are all fluid and all over the place, but one thing it does show you, my constituency and up and down the country, is the risk of a hung parliament and that is a very real risk if you vote any other way than Conservative.

“But we’ve got a really positive plan to get Brexit done, to get the country moving forward, and I’m confident taking that to the voters.”

Ms Harding has tweeted that suggestions Mr Raab – and even Boris Johnson – could lose their seats are “reasons to be (cautiously) cheerful” and urged constituents to vote tactically.

She also accused Mr Johnson of giving “bare-faced lies” in an interview with LBC.

Of this week’s coming Nato summit, Mr Raab said: “People can have criticisms of Nato [and] it does need to adapt, but the answer is to reform it and to strengthen it ... We certainly shouldn’t be saying it should shut up shop, which is what Jeremy Corbyn’s position is.”

Asked if there was “nervousness” over Donald Trump’s visit during the election campaign, he said: “I don’t think so. We’re proud that we’re hosting the leaders’ summit here.”

He added: “I’m not going to give succour to some of the anti-Americanism we’ve heard from some of the other parties. The US is our closest and oldest ally, we work very closely with them.”

What the Tories really want to do, he said, is “bring our European, our American friends together because we think we’re stronger when we stand shoulder to shoulder”.