Nigel Farage, the Ukip leader, is on the verge of declaring he will stand in South Thanet in next year's general election, after local party officials in the constituency conceded he was on the shortlist.

There had been plans earlier in the week for the shortlist for the selection on 26 August to be published on Friday.

But Ukip national officials delayed the announcement, possibly to avoid a crowded newsday and the danger that he might seem to be following another of the country's populist politicians, Boris Johnson, who announced this week that he was seeking a Conservative seat.

Farage, who has a limited range of seats from which to choose, has already said he will probably stand in South Thanet, where the Tory MP Laura Sandys has announced she is standing down. The Tories have replaced her with a former Ukip member in an attempt to defend the Conservative vote from a Farage assault.

Farage has said he wants to be close to London's TV stations during the election campaign, requiring that he find a seat in the south-east. His only other serious option has been Folkestone and Hythe, in Kent.

The official Ukip Facebook page for South Thanet admitted there had been a late change in thinking: "Sorry folks. Change of plans. So many last minute applications to stand in South Thanet that we have to put off the announcement of shortlisted candidates until we have interviewed everyone. Apologies if we caused excitement. Hustings will still be on 26th August."

A poll by Survation commissioned by a Ukip supporter put the party second in the constituency. A more recent poll, conducted on behalf of the Tory peer Lord Ashcroft, suggested that Ukip was on course to win the seat as long as Labour voters did not vote tactically to keep the Ukip candidate out of parliament. It put Ukip on 32%, the Tories on 30%, Labour on 27%, the Lib Dems on 4% and the Greens on 5%. The poll showed little desire among supporters of any of the parties to vote tactically, but did not take into account the impact of Farage being Ukip's candidate.

The only other seat Ukip is on course to win, according to the Ashcroft polling, is Thurrock, where Ukip has already selected a candidate.