Mr Davies, 51, is standing for Boris Johnson’s party again despite his conviction and a subsequent recall petition signed by 20 per cent of voters demanding he be ejected from the seat.
The Brexit Party is hoping to steal votes from disaffected Tories with its candidate, former local police superintendent Des Parkinson, 71.
But a party spokesman conceded that the ‘Boris Bounce’ from the new Prime Minister’s appointment last week could see them run close.
However he also pointed to Mr Johnson’s comments in Wales yesterday that Britain could remain in the customs union and single market for another two years after Brexit, suggesting a negotiated deal with Brussels was still possible.
The spokesman said: ‘They put up a guy who is busted, which is extraordinary.
‘They will try to point the finger at us but they only have themselves to blame, putting up someone who is busted like that.
‘Secondly they must realise from results like this that unless they deliver on the promises made (on Brexit) they will not be the governing party.’
Mr Johnson made a fleeting visit to Brecon yesterday evening, attending the offices of the BVG Group with Mr Davies.
Mr Johnson made a fleeting visit to Brecon yesterday evening with Chris Davies, who was convicted of expenses fraud earlier this year
A swing of 9.8 per cent would be needed by Lib Dem candidate Jane Dodds to win the seat, which saw a majority of 8,038 for Mr Davies in 2017.
It is the sort of swing which, were it to happen at a general election, could see the party pick up around a dozen seats from the Tories.
However, a poll of the area by the Number Crunching Politics website last week suggested that the Remainer party is on course to achieve a 14 per cent swing from the Tories to 43 per cent.
It puts the Tories in second on 28 per cent, ahead of the Brexit Party on 20 per cent, with Labour and the Monster Raving Loony Party coming in ahead of Ukip.
But it was done before Mr Johnson, on a visit to Wales yesterday, indicated that some elements of Theresa May’s withdrawal deal could be revived – including a transition period designed to soften the impact on business of leaving the EU.
Mr Johnson repeated his determination to deliver Brexit by October 31 and said it would be the EU’s fault if the UK ended up leaving without a deal. ‘It is their call,’ he said. ‘It is up to them if they want us to do this.’
Defeat for the Conservatives in Thursday’s by-election in Brecon and Radnorshire would see the Government’s working majority in Parliament shrink to just one.
There are currently 320 MPs who – on paper – would back the Government in a crunch vote in the House of Commons – 310 Tories and 10 members of the DUP.
The DUP agreed to support the Conservatives in certain key votes, such as confidence motions and Budgets, as part of a deal reached in the aftermath of the 2017 general election.
Set against this combined total of 320 MPs are 318 MPs from all other parties.
The seat of Brecon and Radnorshire is currently vacant, so whoever wins the by-election will increase by one either the Government’s tally of MPs or those of the opposition.
The Liberal Democrats are favourites to win the seat, and, were they to do so, the opposition tally would increase from 318 to 319.
With the Tories and DUP unchanged on a combined total of 320, this would reduce the Government’s majority from two to one.
These totals do not include Sinn Fein’s seven MPs, who do not take their seats in the Commons, and the Speaker and three Deputy Speakers, who do not vote.
The Lib Dems held the seat of Brecon and Radnorshire from 1997 to 2015, since when it has been held by the Tories.
The party won 49 per cent of the vote in 2017, compared with 29 per cent for the Lib Dems, 18 per cent for Labour, 3 per cent for Plaid Cymru and 1 per cent for Ukip.
In this week’s by-election, Plaid Cymru is not standing and has instead urged its supporters to vote for the Lib Dems. The Green Party has done the same.
Both parties have stated that they want to try to maximise the chance of success for the Lib Dems.
The result of the by-election is expected to be declared at around 3am on Friday morning.
Who are the candidates in the Brecon By-election?
Brexit Party: Des Parkinson. The retired Dyfed-Powys Police chief superintendent, 71, who wants to cut local council tax and opposes wind farms being built in the attractive rural area. A former Ukipper he ran unsuccessfully to be the area’s Police and Crime Commissioner in 2016. He attacked Boris Johnson today, writing in Politics Home that ‘if he really wanted a clean Brexit he would have asked the tainted Tory to stand down’.
Welsh Conservatives: Chris Davies – The 51-year-old former MP for the seat. In April this year the ex-auctioneer, who is married with two young children, was given a community order after admitting two charges of expenses fraud over false invoices for photographs, sparking a recall petition and this by-election. A Brexiteer who has been backed by the party despite his conviction, including a brief visit by the Prime Minister yesterday.
Welsh Labour: Tom Davies. The Brecon born and raised lawyer, 29, sits on the town’s council. He trained as a barrister and works in Cwmbran, while living in Brecon. He’s a fluent Welsh-speaker and rugby fan. He supports a second referendum but is not expected to win. Labour is projected to finish fourth behind the Lib Dems, Tories and the Brexit Party tomorrow.
Welsh Lib Dems: Jane Dodds. The 55-year-old married child protection social worker and Welsh Lib Dem leader is the favourite to take the seat which was held by the party as recently as 2010. She is also a Welsh-speaker and was born and raised in Wrexham in the north of the country. She won the candidacy after a vote of party members and contested Montgomeryshire in 2015 and 2017.
Ukip: Liz Phillips. The former personal assistant to former Ukip leader Gerard Batten lived for a long time in Rhayader in the constituency but currently lives in Kent. She faces a struggle to win votes from the Brexit Party. She previously contested the seat at the 2001 and 2005 elections – on the latter occasion finishing last.
Monster Raving Loony: Lady Lily The Pink. Representing the perennial election also-rans, Lily, who lives in Brecon, is targeting people not planning to vote because they don’t like the more mainstream candidates, using the slogan ‘if you don’t know what to think, vote Pink’.