A battle has erupted over who will represent the Liberal party in a byelection sparked by the resignation of the former deputy Victorian leader Sam Groth, with local branch members to be denied a vote.

Guardian Australia can reveal that a majority of the party’s state executive (formerly known as the administrative committee) is set to back Mornington Peninsula’s mayor, Anthony Marsh, as Groth’s successor in a vote planned for 24 February.

Groth, a former professional tennis player, had planned to quit politics at the November election amid party infighting, but brought his resignation forward to last week, triggering a byelection in Nepean. The date is expected to be announced by the speaker, Maree Edwards, this week.

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Marsh only joined the Liberal party on 10 February, and was given special dispensation by the executive on 12 February to seek preselection, despite the usual 12-month membership requirement.

Rather than a ballot of local branch members, the decision will be made by the 18-member state executive and six members of the Nepean local executive.

In a statement, Marsh confirmed he had applied for preselection and spruiked his decades-long connection to the electorate.

“I went to school here, have lived here, built my business serving local clients, and have worked and represented this community over many years, including in local government and as mayor,” Marsh said.

“I have been encouraged by locals who value strong local representation for Nepean at a state level, and that sense of service to the community has guided my decision.”

He will face former party candidates David Burgess, Briony Camp (nee Hutton), Nathan Conroy and Bree Ambry, according to senior Liberal sources unauthorised to speak publicly.

One senior Liberal source said bypassing the branch “wasn’t ideal”, but there wasn’t enough time to hold a plebiscite, which could take up to three weeks to organise.

“One Nation and the teals are already on the ground right now,” they said.

Another pointed to Marsh’s 70.43% first-preference result in his ward at the 2024 local government elections, where he defeated Despi O’Connor, who had run as an independent in Flinders at the 2022 federal election.

“Anthony has already proven he can beat a teal,” they said. “He’s exactly what we need in this seat: a sensible, centre-right candidate with local ties.”

However, the move has enraged the local branch, which was already frustrated by Groth’s early departure. One local member said the byelection would cost the Liberal party between $300,000 and $500,000, and taxpayers $2m.

They said the branch was “up in arms” about not being involved in the selection of his replacement.

Another described Marsh as a “Sam Groth 2.0”, noting the tennis player had also received special dispensation to run in the seat.

“We’ve seen the disastrous consequences of preselecting candidates without deep party ties, and we’ve gone and done it again,” they said.

Nepean is considered a safe Liberal seat with a 6.4% margin, but challengers are circling: One Nation has confirmed it will field a candidate, and Independents for Mornington Peninsula are searching for a contender. Labor, however, is not expected to run, having sat out byelections in seats it doesn’t hold for more than two decades.

It will be the first major test for the Liberal leader, Jess Wilson, who took on the role after a successful spill against Brad Battin in November and vowed to unite her divided party.