More than 60,000 people have signed a petition calling for 20mph speed limits for residential roads in Wales to be scrapped.
On Sunday, Wales became the first country in the UK to drop the default speed limit from 30mph to 20mph for restricted roads.
It is predicting the change would save up to 100 lives and 20,000 casualties in the first decade.
Lee Waters, deputy minister for climate change, said: “It’s simple – slower speeds save lives and helps create safer communities for those that live there.
“Evidence shows that a vehicle travelling at 30mph will still be travelling at 24mph in the time it would take a car travelling 20mph to stop.
“We know decisions like this can be unpopular and we know that change is never easy, but what’s one minute on your journey time if it saves a life and reduces a lifetime of human misery for families affected.”
On Monday, Mr Waters joined pupils from Albany Primary School in Cardiff, which is located on a busy high street, for their walk to school.
Headteacher Wil Howlett said: “Many of our pupils have a very busy commute to school having to negotiate high volumes of traffic and parked cars.
“Reducing the speed limit will not only help make this journey safer but will also help to encourage more children and their parents to walk and cycle.”
Not all 30mph roads will see their speed limits reduced as councils have the power to exempt certain roads from the scheme.
The project is costing around £33 million to implement and has proven controversial, with reports of the new 20mph signs being defaced in areas including Conwy, Gwynedd, Newport, Torfaen, Wrexham and Flintshire.
The Welsh Conservatives have opposed the scheme and tabled a motion in the Senedd to halt the rollout but were defeated last week.
They cited Welsh Government documents that estimate the cost to the Welsh economy of increased journey times from lower average vehicle speeds at anywhere between £2.7 billion and £8.9 billion.
They want to see more “targeted measures” rather than the introduction of the default speed limit with exemptions, and likened it to the ultra low emission zone (Ulez) in London.
Natasha Asghar, the Conservative shadow transport minister, said: “The new blanket 20mph speed limit has been in place for just one day and already people have had enough of it.
“For more than 60,000 people to sign a petition within 24 hours shows the extent of public outrage towards Labour’s madcap policy.
“This highlights that there has been little to no consultation with the general public, the Labour Government have clearly avoided all public scrutiny in a bid to get their socialist agenda pushed through.
“Labour and Plaid Cymru have refused to listen to public opinion and are continuing to wage their anti-worker, anti-road and anti-motorist agenda.
“With this ludicrous policy forced on the people of Wales, Labour can still U-turn on this disastrous rollout and deliver what Wales wants by scrapping blanket 20mph zones across Wales.”
As more than 10,000 people have signed the petition, it will be sent to the Senedd’s petitions committee for a debate.