Anger has boiled over among federal Nationals MPs during a party room meeting dominated by criticism of deputy leader Bridget McKenzie.

Key points: Bridget McKenzie is facing criticism from some backbenchers for her handling of the agriculture portfolio

Bridget McKenzie is facing criticism from some backbenchers for her handling of the agriculture portfolio Senator McKenzie became the Agriculture Minister after the federal election, replacing David Littleproud

Senator McKenzie became the Agriculture Minister after the federal election, replacing David Littleproud Some backbenchers have not ruled out a leadership spill

Backbenchers, who did not want to speak publicly, have told the ABC they were frustrated with her leadership style and have not ruled out a challenge to her position.

One MP said it was a "waste of time" contacting Senator McKenzie because she "never gets back to you", while another said she "couldn't organise a piss-up in a brewery".

Senator McKenzie was elected as deputy leader in 2017 and took over the agriculture portfolio from David Littleproud in May this year, although Mr Littleproud still oversees water and drought policy.

She was not at Monday's meeting because she attended Senate Estimates.

Another Nationals MP said the question of her leadership might have been brought to a head had she been at the meeting.

"We are facing one of our biggest tests of government in this drought," he said.

"It has the potential to be a national disaster and needs our top minds in those positions of drought, water and agriculture. And right now, agriculture is the hot seat and we need her to do a better job."

Frustrations grew last week after Senator McKenzie brought forward the introduction of a dairy industry code of conduct, following pressure from One Nation leader Pauline Hanson.

The code was one of Mr Littleproud's initiatives and was designed to give farmers more market power in their dealings with milk processors.

Queensland MPs, who have been lobbying for the code's introduction, are fuming that Ms Hanson's demands were met so swiftly.

Bridget McKenzie has served as deputy leader to Michael McCormack and Barnaby Joyce. ( ABC News: Ross Nerdal )

Senator McKenzie is not without support in the party room.

Some MPs are tired of agitation within its ranks and would prefer stability instead of leadership chatter.

There is also concern that removing a woman from a top leadership position would be a bad look.

But frustration with Senator McKenzie's performance has been simmering for months and outside the party room, some industry sources are concerned about the split of the agriculture portfolio from water and drought.

Those concerns are not felt by CropLife chief executive Matthew Cossey, who said Senator McKenzie had been "engaged and enthusiastic" since taking on the role of Agriculture Minister.

"While on a number of these issues we aren't in agreement and are in conflict, we've actually found her good to deal with," he said.

Tensions continue to build within the Coalition over drought funding, with the Nationals canvassing plans to push for bigger funding announcements for struggling farmers and communities.

The National Farmers' Federation will this week release further details of its drought policy, which has been handed to the Government for consideration.

Nationals MPs were caught off guard last week when Prime Minister Scott Morrison announced a new lump sum payment for the Farm Household Allowance live on radio, at the same time as the Deputy Prime Minister Michael McCormack was holding a press conference on the same issue.

The ABC has contacted Senator McKenzie's office for comment.