The Liberal senator Jane Hume joked she would “have to speak a lot slower” if she joined the Nationals, saying she was “too fond of good coffee and free markets” to join the regional party, after David Littleproud said he was open to more conservatives joining his ranks.

It comes amid a long-running and damaging period of soul-searching for the opposition, with members of the Liberals and Nationals reportedly considering switching parties, starting a new conservative movement, or assessing leadership options.

Hume’s tongue-in-cheek comments have been criticised by Labor’s regional development minister Kristy McBain, who accused the Melbourne-based politician of insulting regional Australia – accusing her opponent of being “smarmy” and “arrogant”.

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Littleproud, the Nationals leader, told the Australian newspaper he was open to accepting party-switching colleagues, claiming his movement – with 15 of 43 Coalition MPs in the lower house and four out of 27 in the Senate – had “more influence than ever”.

It comes amid simmering tension between the two Coalition parties themselves, including Jacinta Nampijinpa Price’s clumsy switch from the Nationals to the Liberals, and disagreements over net zero and climate change which led to a brief dissolution of the Coalition in May.

Hume, a former minister now on the backbench, was asked on Channel Seven’s Sunrise whether she would take up Littleproud’s offer to join the Nationals.

Hume grinned and deadpanned: “Well, look, I do look very fetching in an Akubra, Nat, I’ll tell you that much. And I’d have to speak a lot slower and talk about the regions more often down in cocky’s corner.”

“But, look, no. To be honest, I am too fond of good coffee and free markets to join the National party.”

Hume’s office later clarified she was teasing her colleagues in the Nationals, and didn’t intend for her comments to be a dig at regional Australia more generally. But McBain, based in the regional electorate of Eden-Monaro, criticised Hume’s comments.

“Senator’s Hume’s attempt at humour clearly shows who the Liberal party of today is – out of touch, arrogant, and completely focused on themselves. It’s one thing to have a crack at their Coalition partner, it’s another to insult the entirety of regional Australia,” she said.

“People in Geraldton, Geelong and George Town don’t need smarmy lectures from arrogant Liberals who think once you step out of an inner-Melbourne laneway, we are all slow-talking drongos.”

McBain welcomed Hume to her electorate, where she offered to “shout her an excellent chai latte from my local cafe Infuse in Tura Beach, a macchiato from 4 Seeds in Queanbeyan or a croissant from Honorbread in Bermagui.”

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Hume, responding to McBain’s criticism, shared another tongue-in-cheek response.

“I’d be happy to judge the best coffee in regional Australia competition, and keen to include meat pies and vanilla slices,” she told Guardian Australia.

“Please send me the list Kristy. Keep in mind though, that I like to take my coffee with a dose of humour.”

Despite some Liberals and Nationals still keen to dissect the election result and continue flirting with starting new conservative movements, senior Coalition members are urging their colleagues to start looking toward the next election rather than remaining mired in long-running self-reflection.

Shadow minister James Paterson said this week his party “must call time on the apology tour” and begin focusing on holding the government to account. The opposition leader, Sussan Ley, issued a statement on Thursday which said the Coalition must “reconnect with the Australians with whom we have lost touch, and to develop new policy solutions to the challenges of our time”.

“We need a new Liberal agenda, based on our enduring values, that meets this moment,” she said.