MP for Northland Wintson Peters is accusing the National Party of double-crossing Northlanders during this year's by-election when it promised to double-lane 10 bridges in the region.
National promised in March that it would upgrade the bridges on Northland's Twin Coast Highway over the next six years making them safer for locals and tourists.
But the Transport Agency (NZTA) yesterday announced a $13.9 billion plan for spending on roads and public transport across the country over the next three years in which it committed to double-laning just four of the bridges.
Mr Peters said the National Government did not do its homework when it announced the 10-bridge programme and now has some serious questions to answer.
"You should go and ask the Prime Minister and Mr Joyce about why they went up to the north, and misled all those people up there and told them blatant lies, without any costing, any engineering, and any approval from the authority that would aprove the bridges in the first place.
"I think they went up there and they thought they could bull-dust the people of Northland, and I'm going to make sure the people of Northland get to know all about this."
But Prime Minister John Key said the Government would deliver on its election promise.
He said the Transport Agency and the Government agree on double-laning seven of the bridges.
"There's some dispute over the other couple, two or three of them, but that's not unusual, quite often transport [the NZTA] say to us 'we don't think you should do a particular bridge or a particular road', and the Government over-rules them because we say there's a wider interest here," said Mr Key.
"So I'm quite confident the 10 will be fixed."
The Transport Agency has told Transport Minister Simon Bridges that one of the bridges could not be double-laned as it ran between two large kauri.
Nevertheless, he too remained confident all 10 bridges will eventually be built even if the money had to come from elsewhere.
"We've still got other options like funding them from the Crown."
Labour Party leader Andrew Little said the Government needed to honour the promise it made to Northland.
NZTA has also announced it will spend $460 million in Northland over the next three years and part of the funding will enable councils to carry out dust mitigation measures on unsealed roads.
The dust generated by logging trucks on unsealed roads has led to protests in Northland, and the agency says it will also sponsor a research project into the effects of dust.