Rishi Sunak has been told to scrap his controversial voter ID decision by nearly 120,000 people.
Campaigners warn that tens of thousands will find themselves locked out of next month's local elections by the controversial new measures.
New rules in England mean people must now show photographic identification when they go to their local polling station.
But the Government admits that around two million people don't have the suitable documentation, while it is estimated that a quarter of voters don't even know about the change.
A petition signed by 118,00 was presented at Downing Street calling on ministers to abandon the plan, which it is feared will benefit the Tories when voters go to the polls.
Former Lib Dem MP Tom Brake, who heads campaign group Democracy Unlocked, told The Mirror: "We believe there's a real risk that tens of thousands of people will be turning up at polling stations next month and getting turned away.
"It's a threat to our democracy. If just one person gets turned away, that's bad.
"Council elections can be decided by one, two or three votes. If a polling station is turning away 20 or 30 people that could make all the difference."
He called on the Government to plough the £180 million it has earmarked for the scheme into voter registration.
And Green Party peer Baroness Jenny Jones said: "It's clearly designed to stop people voting if they don't vote Tory. The Government is running scared. This will have a massive impact"
An older person’s bus pass can be used but, confusingly, not a young person’s rail card. Campaigners claim the criteria has been chosen to suppress turnout by young people more likely to vote Labour.
Mr Sunak has claimed the under-fire policy would help ensure elections are "high-integrity processes'' despite there being no evidence of large-scale voter impersonation.
Asked whether it would cause issues, including "angry complaints", the Tory leader said: "No, this is something that has been in the tray for a while now so it's been well-looked at".
"I think, [we don’t need to] rehash all the arguments why this is a sensible thing to do."
He told Conservative Home: "I think most people agree our elections should have some form of identification so that we can make sure they are high-integrity processes."
But last week The Mirror revealed that police issued just one caution for electoral fraud in the whole of 2022 - raising questions over the multi-million pound policy.
Mr Davis said voter ID risks having a "more deleterious effect" on voting than the issue the new law is attempting to solve, and urged ministers to re-think.
Labour's Deputy Leader Angela Rayner has previously described the policy as "expensive and unnecessary" and warned voters risks being caught out while renewing documents such as driving licences and passports.
She added: "No one should be missing out on democracy because this Government can't keep our public services running effectively.
"If voters don’t have the Government’s required photo ID, the easiest way to vote is by signing up for a postal vote.”
