At a public meeting in Southampton on Saturday, New Forest East MP Dr Julian Lewis said he would speak on the issue in the House of Commons, and call on Health Secretary Jeremy Hunt to intervene.
As well as Mr Lewis, the meeting heard from county council leader Roy Perry, Southampton City Council health chief Dave Shields, county councillor David Harrison and south-east MEP Keith Taylor, as well as a number of residents and anti-fluoride campaigners.
The fate of the scheme to add fluoride to the tap water of 200,000 households in Southampton, Rownhams, Eastleigh, Totton, and Netley, is currently the subject of a complex legal wrangle.
Addressing the meeting, Roy Perry reiterated that the county council stood by the result of a 2008 vote in 2008, in which councillors rejected fluoridation.
He said the fate of the scheme was still in the balance, with county lawyers believing it does not even exist due to a mix-up before the Strategic Health Authority was abolished last year.
However, he added: “The moment Public Health England (PHE) say they intend to proceed, that is when I call all of the county council lawyers into my office and ask them how we prevent this by law.”