The ambitious Scouser will look to overhaul the union and restore it as a main player within the Trades Union Congress, pulling it out of the pariah status it acquired when it refused to back the workforce agreement. It may take a bit of fancy footwork to come back into the fold while maintaining face, but Mr Sinnott is confident he is the man to do it.
He has plenty of experience of being on the outside. Despite being NUT deputy general secretary, he has been effectively frozen out of national union affairs by Doug McAvoy and been left to concentrate on international issues and local industrial action.
Now firmly on the moderate wing of the union, he was once a Communist party member, something he stresses was "a very long time ago". Today, backing from the NUT's largest faction, the soft-left "Broadly Speaking", makes him favourite - though not with the bookies - to win the contest. His performance at an election hustings session at the Easter annual conference prompted bar-room pundits to comment that he looked like a general secretary in waiting.
Mr Sinnott, 52, has put a call for a single union at the centre of his campaign. Despite the message "Our aim - Professional Unity" being displayed on NUT leaflets and posters, it has not been a high priority for Mr McAvoy, who recently accused fellow classroom teaching unions of betrayal.
Mr Sinnott is married with two children, both in their 20s, supports Everton and enjoys cycling. He was born in Liverpool and educated at West Derby comprehensive in the city before reading social sciences at Middlesex polytechnic and taking his PGCE at Edge Hill college, Lancashire.
He began his career as an economics and business studies teacher in 1975 at Shorefields comprehensive in Toxteth, Liverpool before moving to Broughton high in Preston.
He joined the national executive in 1986, became national president in 1994 and was elected deputy general secretary the following year. A re-election in 2000 gives Mr Sinnott a formidable record in fighting NUT contests.
Ladbrokes has made him even-money favourite while William Hill is offering 54.