Wes Fang has explained why the National Party opted against contesting the Kiama by-election while also having a dig at NSW Opposition Leader Mark Speakman, who is under pressure to retain his job.

Fang, a Member of the Legislative Council who is also the Deputy Opposition Whip, was interested in being parachuted into the Kiama electorate as the Nationals' candidate but the Party has decided to not contest the seat, clearing the way for the Liberals to attract the lion's share of the conservative vote.

"With Labor seeking to field a candidate, as well as it being optional preferential voting at the state level, should both the Nationals and the Liberals contest, it would likely ensure the seat is lost for the Coalition, given the expectation of splitting the vote between us," he told The Bugle.

"It was my belief, given the last two by-elections in Wagga Wagga and Pittwater, where the Liberals had issues with their former candidates having to resign in disgrace, then subsequently losing those seats, the best result for the Coalition, was to allow the Nationals to contest the Kiama by-election instead.

"Unfortunately, history demonstrates commonsense does not always win the day."

Speakman responded on Friday after announcing Serena Copley as the Liberals' candidate by saying his party did not decide whether the Nationals would run and that decision was made by them after he had consulted their NSW Leader, Dugald Saunders.

"Under our Coalition agreement when a seat is vacated like Kiama, the Liberals and Nationals consult each other about whether either of us will run, both will run or one or the other," he said.

"I had those friendly discussions with Dugald Saunders. They have made the choice not to run in this by-election."

The Liberals lost the Wagga Wagga by-election in 2018 after sitting MP Daryl Maguire resigned after an ICAC inquiry while they also conceded the Pittwater seat to independent candidate Jacqui Scruby last year following Rory Amon's resignation due to child sex offences.

Speakman is failing to make an impact on Premier Chris Minns in the opinion polls and the Coalition appears headed for another election loss in 2027.

Fang questioned whether Speakman's insistence on fielding a Liberal candidate ahead of the Nationals in Kiama was the right move.

"I am unsure, if this is crazy-brave, or simply just crazy on behalf of Mark Speakman," Fang added.

"Mark's grip on the leadership is already slipping and a loss would likely reinforce the growing criticisms from within his own party about his lacklustre leadership, cardboard personality and inability to connect on a human level with anybody other than those who hold a law degree.

"Questions would be asked as to why there was an insistence for the Liberals to run, given their track record in these sort of by-elections, when the Nationals were perhaps better placed to contest it, given our unblemished record."

Fang, who hails from Wagga Wagga, recently visited the Kiama electorate and had considered throwing his hat into the ring but thought a locally based candidate would have been a better option.

"For the record, while it was a genuine honour that people may have considered I might have been a candidate for such a spectacular electorate and interesting, diverse community, the Nationals have always believed that you need local champions who are embedded in their communities for many, many years," he said.

"I would not have been the candidate.

"We would've had an amazing local champion, for whom the community could have been extraordinarily proud."