Victorian Liberal upper house MPs Moira Deeming and Ann-Marie Hermans are to face preselection challenges, as senior party members sound out a former journalist to run against Renee Heath.

Guardian Australia has confirmed from three sources not authorised to comment publicly that Dinesh Gourisetty, a prominent figure in Melbourne’s fast-growing Indian community, will nominate for preselection in the western metropolitan region against Deeming.

Nominations for Liberal upper house preselections close on 14 January, with voting to take place across two weekends in March, before the state election in November.

In the south-east metropolitan region, Hermans will also face a challenge. Three sources said several names were in the mix for the No 1 spot on the ticket, including the former Dunkley candidate and Frankston mayor Nathan Conroy, former Mordialloc candidate Phillip Pease and Manju Hanumantharayappa, who was No 2 on the Liberal party ticket in 2022 and narrowly missed out on the final upper house spot.

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Conroy is also being sounded out to run in Nepean after the shock resignation of the party’s deputy leader, Sam Groth, on Monday, one senior Liberal figure said.

Hermans told Guardian Australia she had heard “rumours and complaints from party members” about a challenge but had not been contacted directly by any potential candidate.

“If I am being challenged, then my opponent is already showing themself to be unprincipled and gutless,” Hermans said.

She said the second spot on the ticket was “gettable” and should be contested.

“I have worked hard, taken the challenge to Labor, tilled new ground in red heartlands, and I would consider it a major failing of the party if I am to be penalised and challenged for being conscientious and committed to fighting tirelessly to represent the Liberal party and help my local community,” Hermans said.

Deeming supporters have said she will “not go down without a fight”.

The MP declined to comment when contacted by Guardian Australia as party rules prohibit candidates from commenting publicly on preselections.

“So far she hasn’t lost,” one supporter said, pointing to Deeming’s successful defamation case against the former opposition leader John Pesutto.

The party loaned Pesutto $1.5m to help pay the $2.3m in legal costs, which is now subject to a court challenge.

Gourisetty is listed on Pesutto’s parliamentary register of interests as a donor to his legal fund. He previously challenged Deeming at the 2022 preselection, having earlier run in the No 2 spot in 2018 and as the Liberal candidate for Tarneit in 2014.

At the 2022 contest, he failed to secure the backing of the then state party president, Robert Clark, and his allies, in part due to breaches of the food safety act he pleaded guilty to in 2019.

Since then, Gourisetty has built significant support across the western suburbs branches that make up the region, while the party’s executive committee has skewed moderate under the new president, Philip Davis.

Sources close to Gourisetty say he has the numbers in eight of the region’s 11 branches but Deeming’s supporters dispute this figure. They say she has strong grassroots support and endorsements from high-profile Liberal figures.

Meanwhile, in eastern Victoria, two sources confirmed senior Liberals had approached journalist and author Sue Smethurst to run against Heath. She previously ran for the spot in 2021. Smethurst declined to comment to Guardian Australia.

Heath’s supporters downplayed the prospect of a challenge, pointing to her strong support in local branches and in the party room, including her recent promotion to the shadow cabinet.

Steve Brooks is expected to secure enough support to replace long-serving MP Wendy Lovell, who resigned on Monday, in Northern Victoria. The No 2 spot on the north-east metropolitan ticket will also be filled after MP Nick McGowan’s decision to contest the lower-house seat of Ringwood.

Victorian Labor has delayed its upper house preselections as it awaits an outcome on group voting tickets and hashes out its stability deal between factions.

Gourisetty, Conroy, Hanumantharayappa, Pease and Heath were approached for comment.