The government has picked up another Senate crossbencher to add to its numbers, with Tasmanian independent Steve Martin announcing he has joined the Nationals.

It is the first time the party has had representation in that state since the early 1920s, when William McWilliams was briefly leader of the Country Party.

Although it is to the Coalition’s advantage to have an additional senator locked in, and one less independent with whom to negotiate, in practice the change does not affect things significantly.

Martin’s move takes the Coalition to 31 in the Senate, out of a 76-member chamber. It means the government has to get eight of ten crossbenchers to pass legislation opposed by Labor and the Greens. Previously it was nine of 11. Martin has mostly voted with the Coalition and was already committed to supporting the government’s company tax cuts for big business.

He was elevated to Parliament on a countback, following the resignation of Jacqui Lambie in the citizenship crisis, but he never sat as a representative of the Jacqui Lambie Network, becoming an independent.

Earlier, Senator Lucy Gichuhi moved from the crossbench to the Liberals. She has come under threat for a winnable place on the South Australian Liberal ticket.

Martin said on Monday that what drew him to the Nationals was “their focus on key issues such as natural resources, teamwork and, of course, people”. He said the Nationals had a record of looking after rural and regional communities and Tasmania was rural and regional.

Nationals leader and Deputy Prime Minister Michael McCormack said Martin’s joining was “reinvigorating the National Party in Tasmania”.

Recalling the long period since the party had had representation there – before the Tasmanian tiger was last seen in the 1930s – McCormack said: “I liken Steve a bit to the Tasmanian tiger, inasmuch as he will be a tiger for regional development, an absolute tiger in there fighting for the interests of Tasmanians.”

Martin said he had no “deal” with the Nationals although “I hope I get the number one on their election paper”.

It is not clear how Martin, who is up for election at the next poll, would fit with the Liberals’ ticket. Although only Liberal Richard Colbeck is up for re-election next time, sources say Martin’s joining the Nationals does not mean there would necessarily be a joint Coalition ticket. There could be separate tickets.

Lambie, meanwhile, responded to the news with her own tweet on Monday: “I will be running to return the Senate seat to the people of Tasmania who want a truly independent voice in Canberra. Trust me, I am biting at the bit, looking forward to taking the Nats out!”

Michelle Grattan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.