The firebrand MP is known for his staunch opposition to a net-zero emissions target after his party room signed up in a deal with then-Liberal prime minister Scott Morrison in exchange for a sizeable regional funding package.
The Nationals, as the junior coalition partner, are unable to match the Liberals' numbers so bolder policy positions are needed to fight for regional Australians in lower socio-economic areas, Mr Pitt said as he announced his retirement on Friday.
"If we look at net zero in particular ... I think Labor has moved too far, too fast and at too much cost at a time when the Australian people simply can't afford it," he told Sky News.
Mr Pitt, who holds the Queensland seat of Hinkler on a 10 per cent margin, decided to retire after an "unexpected opportunity" arose.
But that did not stop him from criticising Nationals Leader David Littleproud who he said, in a parting shot in The Australian, needed to "stand up and be strong" and give the party clear priorities and direction.Â
However, Mr Pitt didn't go as far during his Sky interview, saying "my commentary is always about policy, it's never about personalities".
"My frustration bucket has filled slightly over a long period of time," he said when asked about being relegated to the back bench under Mr Littleproud.
"I'm someone that likes to get things done and I like to be in the heart of it and making decisions, and it's just time to move on," he said.
There is friction between sections of the Nationals and the Liberals over energy policy and a commitment to net zero, as climate change shapes up as a major battleground in the federal election due by May 2025.
Nationals Deputy Leader Perin Davey thanked Mr Pitt, adding the Nationals remain committed to net zero although this "has always been contingent upon technology agnostic approach", she told AAP.
"And if it wasn't for net zero we wouldn't be talking about nuclear and we need nuclear," she added.
Mr Littleproud wished Mr Pitt all the best.
Despite some private opposition to net zero in the Nationals party room, most recognise the political reality of maintaining the 2050 target because they need the Liberals to win city seats to form a coalition government.
Opposition Leader Peter Dutton denied there's friction between the coalition partners, saying Mr Pitt was frustrated on the back bench and had decided to take a private sector offer.
Retiring Nationals backbencher Keith Pitt says it's just time to move on. (Mick Tsikas/AAP PHOTOS)
The coalition has unveiled a $330 billion nuclear energy policy that would deliver seven reactors across Australia with nuclear making up more than a third of the energy mix by 2050, in contrast to Labor's focus on renewable technology.
But it's been slapped down by clean energy groups which have branded a nuclear industry start-up as too expensive while arguing that renewables harness Australia's vast wind and solar resources and are the cheapest option.
Mr Pitt joins a growing list of Liberal and National MPs who have either quit or aren't recontesting.
These include Liberal frontbenchers Karen Andrews, Simon Birmingham, Linda Reynolds and Paul Fletcher and Nationals MPs David Gillespie and Mark Coulton.
The coalition has also lost MPs to the crossbench where they sit as independents, including ex-Nationals Andrew Gee, who went against his party and supported the Indigenous voice to parliament.
Liberal MPs Russell Broadbent and Ian Goodenough shifted after losing preselection while Queensland senator Gerard Rennick quit the LNP to start his own party after being booted from the Senate ticket.
Victorian Liberal senator David Van was forced out after allegations of sexual harassment, which he denies.
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