New Zealand's big four Australian-owned banks face increasing political pressure to pass on more of last week's surprise cut in the Official Cash Rate to floating rate borrowers, particularly struggling dairy farmers.ANZ set the tone after Thursday's 25 basis point rate cut, passing on only ten basis points to floating mortgage borrowers, citing higher funding costs. Westpac copied ANZ's example and National Australia Bank's BNZ has not passed on any of the cut. Commonwealth Bank of Australia's ASB passed on 20 basis points of the cut.The banks' decisions not to pass on the cut fully flew directly in the face of comments by Reserve Bank of New Zealand Governor Graeme Wheeler, who told a Parliamentary Select Committee on Thursday he expected all of the cut to be passed on to floating rate borrowers.The pressure ramped up on Monday and Tuesday as it became clear the banks had not passed on any of the cut to New Zealand's debt-ridden dairy farmers, particularly given the Reserve Bank cited their plight as one reason for the official rate cut. As of Tuesday night, none of the Australian-owned Big Four banks or Rabobank, another big rural lender, had passed on any of the rate cut to dairy farmers with floating rate rural loans.Finance Minister Bill English initially said on Sunday he was not concerned by the lack of bank pass-through of the rate cut, but by Tuesday he was putting his views more bluntly."There's an expectation that a reduction in OCR will get passed on. It might take a bit of time and competitive pressure for that to happen," he said on Tuesday when asked about banks not passing on the cut to farmers.Agriculture Minister Nathan Guy also pointed to public pressure on the banks."What tends to happen here is there is a bit of public pressure that is applied. Right now farmers will be watching this space very, very closely," Guy said.Asked what would happen if the banks did not pass it on, he said: "What tends to happen in a situation like this is that public pressure tends to build and that's something that the banks will be very, very mindful of."The main Opposition Labour Party ramped up the pressure in Parliament, saying it would consider regulation to force through interest rate cuts if it were in Government and accusing the ruling National Party of favouring the banks over farmers.Labour Leader Andrew Little said a Labour Government would initially do some "serious talking" to the banks, which he described as "stiff-arming.""When you are in government you have the power to legislate, but I think you have to have a pretty serious talk to the banks about expectations," Little told Banking Day in Parliament.Asked about the banks' arguments about higher foreign funding costs, he said: "We have a banking centre that, through good and bad, has been extraordinarily profitable, exporting billions of dollars of profits every year and I think, frankly, they can do better for New Zealand."The banks' lack of rate cutting