National's Deputy leader says its economic plan is solid despite widespread doubts.  

The party released its fiscal plan on Friday, Finance Minister Grant Robertson describing it as being built on sand.  

A recent Newshub Reid Research poll found 53 percent of respondents don't think National can pay for their tax cuts.  

The tax plan was also criticised by economists from across the political spectrum.  

Despite the doubters Nicola Willis told Kate Hawkesby the plan has been carefully put together. 

She says there are buffers in place in case parts of the plan go over or under expected cost. 

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