Dearne residents are being urged to check they are registered to vote as changes to the electoral register come into effect next month.
Michael Dugher, Labour MP for Barnsley East, claimed Government changes to the electoral register that will come into effect before Christmas could mean a million people lose their right to vote.
Under the old electoral system, one person in each household completed the registration for every resident eligible to vote.
But when councils transfer to a new register next month, to which everyone has to sign up as an individual, Labour estimates around a million people will fall off the electoral register.
Mr Dugher said: “Parliament Week is a fantastic opportunity to showcase how vibrant and open our democracy is.
“It is so important that people’s voices are heard, particularly when Government changes to the voting system could mean one million people fall off the electoral register.
“I would urge people to check that they are registered to vote. It only takes five minutes and can be done on www.gov.uk/registertovote.”
Parliament Week, which runs throughout this week, sees events being hosted across the country to help engage members of the public in politics.
The Government has defended the voter register change and vowed to work with local authorities to make sure as many people are registered as possible.