Devon and Cornwall's first elected police commissioner could secure the post with as little as 8% of the vote, Labour has warned.
The party's Shadow Policing Minister, David Hanson, has urged the Government to ramp-up its "invisible" publicity campaign on the polls to pick 41 new police chiefs next month.
It is "not going to be good for democracy" if any of the policing figureheads, designed to improve accountability, secure less than 10% of the vote in their region, the MP said.
Speaking to journalists at the Labour conference in Manchester, Mr Hanson renewed his party's unease at the post, but added: "We are in the business now of trying to make this work and drive through our values."
The police authority, which oversees policing, is being scrapped to make way for the US-style commissioner, plus a panel to act as a watchdog. Chief constables will still be in charge of operational policing. In Devon and Cornwall, the post commands an £85,000-a-year salary.
Mr Hanson said: "We have had some concerns about the whole model of police and crime commissioners because one person covering an area like Devon and Cornwall is quite a significant role in terms of interface between the police and the elected person. The police authority in the past would have had people from all parts of that area."
With the elections on November 15, Mr Hanson said: "We want to see people turn out and vote.
"This election period, invisible though it is despite it being a government flagship policy, we are committed to try and raise turnout and make it work.
"Whatever the turnout somebody's going to win this post of police and crime commissioner.
"The person who wins has the authority of that post. But I think the higher the turnout, the more people participate, the more issues that are raised, the stronger that mandate will be.
"We could have potentially a 15% to 20% turnout. We could have somebody potentially winning on 8% or 9% of the vote. That's not going to be good for democracy. These are important elections."
In Devon and Cornwall, Plymouth councillor Nicky Williams will stand for Labour and former Culdrose naval base commander Tony Hogg has secured the Conservative Party nomination.
Former Detective Chief Inspector Brian Blake is running for the Lib Dems, and Brian Greenslade, the Lib Dem leader of North Devon Council, is among a number of independents likely to feature on the ballot paper.
Last week, an open letter to Home Secretary Theresa May signed by Labour, independents and former Liberal Democrat London mayoral candidate Brian Paddick warned of the "lowest turnout in British history".
They want the Electoral Commission to write to every household telling them about the elections and the Government to make sure that broadcasts promoting the elections take place.
"It's a flagship government policy – they have a responsibility for the turnout," Mr Hanson said.
And he did not rule out Labour scrapping the role in future. Mr Hanson said: "This post may work, it may not work."