Oliver Colvile, Conservative MP for Plymouth Sutton and Devonport, said numbers of the prickly creatures had fallen by a third in the last decade.
He said that declaring the hedgehog to be Britain's national symbol might enthuse people to protect it.
But environment minister Rory Stewart questioned hedgehogs' suitability, and said the lion should remain the symbol.
Mr Colvile said his love of hedgehogs stemmed from his mother reading Beatrix Potter's The Tale of Mrs Tiggy-Winkle to him as a child.
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He said: "The principal reason for this prickly animal's decline is due to the loss of habitats.
"Likely factors for the hedgehog demise are the loss of permanent grassland, larger field sizes, use of pesticides and herbicides and a reduction of hedgerow quality."
Mr Stewart responded in the House of Commons: "Do we want to have as our national symbol an animal that when confronted with danger rolls over into a little ball and puts its spikes up?
"Do we want to have as our national symbol an animal that sleeps for six months of the year, or would we rather return to the animal that is already our national symbol, the lion?"
Source: Devon Wildlife Trust
In response to a crashing hedgehog population, a 90-hectare refuge was created this year by the Warwickshire Wildlife Trust.
Funded by the British Hedgehog Preservation Society, the conservation area stretches across a nature reserve, a public park and the surrounding streets.
The trust said that during the 1950s, some 36 million hedgehogs used to snuffle in UK gardens, although there may now be less than a million.
Gavin Williamson, Conservative MP for South Staffordshire, said he was doing his bit to help.
He said: "It's very important to use our gardens which are a specific habitat for hedgehogs.
"Just recently in my own garden I built a hedgehog house. Sadly I have no residents in it but hopefully it will encourage them and the growth of hedgehogs in South Staffordshire."
The "great British hedgehog" should become a national symbol of the UK, an MP has suggested.