Tamworth MP Kevin Anderson had announced his support after a community survey, joining Nationals neighbour, and Northern Tablelands MP, Adam Marshall, as well as Shooters Barwon MP Roy Butler in publicly supporting the bill.

A total of 19 amendments were put forward for the proposal; however, many were knocked back.

Mr Anderson said thousands of people had taken part in his online survey, which showed a "very slim majority" of the community - 50.9 per cent - supported the bill.

However, Mr Anderson said he was supporting a number of changes to the proposal.

"I believe that it is my job to represent the electorate and I wanted this process to be as open as possible," Mr Anderson said.

"The results of the survey showed that while the Tamworth electorate supported the bill, after analysis of the survey responses, including those who have contacted me directly, it is clear that there were some concerns with the original bill.

"As such, I will vote in favour of the bill, as per the electorate wishes, while supporting amendments that will add additional protection for terminations for mothers under the age of 16; ensuring that terminations take place in a hospital to ensure the support measures are in place; and additional requirements for those seeking a termination after 20 weeks."

The amendment to change the threshold from 22 to 20 weeks, introduced by Liberal MP Tanya Davies, was voted down.

The traditionally conservative NSW National Party allowed its politicians to have a conscience vote on the matter.

If the bill is passed by the Lower House, it will move on to the Upper House, where it is expected to be debated on August 20.