When voters head to the polls in Brecon & Radnorshire on December 12, it will be the second time in five months they have been asked to elect an MP.
The first time was in August, when a by-election took place in the constituency.
This was won by the Liberal Democrats, who took the seat from the Conservatives on a massive 12% swing.
Now the Tories have a chance for revenge – and they would need a much smaller swing of just over 2% to take the seat back.
Boris Johnson visited Brecon & Radnorshire on Monday on the campaign trail.
It is one of a handful of constituencies in Wales that could change hands at the election – and the only Welsh seat being defended by Lib Dems.
Jane Dodds won the seat for the Lib Dems in the by-election and is standing again this time, defending a majority of just 1,425.
Her party represented Brecon & Radnorshire continuously from 1997 to 2015, before losing to the Conservatives.
Ms Dodds’ chances of holding the seat may have been boosted by the decision by Plaid Cymru and the Greens not to field candidates.
The same pact was in operation at the by-election.
Instead she is up against the Conservatives, Labour, the Christian Party and the Monster Raving Loony Party.
The Brexit Party, which won 10% of the vote at the by-election, is not standing this time.
If the Lib Dems win Brecon & Radnorshire comfortably, they’ll be having a good night in Wales – and may even be in with a chance of taking the neighbouring Tory-held seat of Montgomeryshire.