Liberal Democrat MP Patsy Calton has died following a long battle with cancer, aged 56.
Patsy Calton: "Spirited and courageous"
The Cheadle MP had presided over the most marginal seat in the UK until she was returned to Parliament on 5 May with a greatly increased majority.
She was last seen at Westminster on Tuesday when she arrived in a wheelchair to take her oath.
Party leader Charles Kennedy described Ms Calton as a "spirited and courageous" politician.
He said: "I wish to extend my most profound sympathies and condolences to the family and friends of the late Patsy Calton following her death.
"In particular all our thoughts are with her husband Clive and their children.
"Patsy was a spirited and courageous MP, and nowhere was that spirit and commitment more evident than in the way she continued to represent Cheadle throughout the recurrence of her illness during the general election campaign, and most movingly when only last week she took her oath in the House of Commons.
"Despite her desperate illness, her determination shone through.
"Cheadle has lost a wonderful constituency MP and the Liberal Democrats have lost a fine representative of our cause."
Ms Calton won her seat with a majority of about 4,000 despite defeated Conservative MP Stephen Day trying to win it back.
She was unable to attend the count at Stockport Town Hall due to cancer treatment.
Liberal Democrats president Simon Hughes said: "This is a real tragedy, Patsy I've known for many years.
"I was born in the seat she came to represent, she had lived there for many years with her family.
"She became not just the MP for Cheadle... but she became a true community MP.
"In her last days, fighting against cancer, she refused to give in, she said 'other people have to fight, I'm not going to give in just because I'm a politician'."
He said there was "no greater recent model of political courage" than Ms Calton.
Francis Maude, Conservative Party chairman, also paid tribute to Ms Calton, who he said was "highly regarded by people from every party".
"Despite her illness she campaigned tirelessly for cancer charities," he said.
"Everyone will have been moved and inspired by the courage with which she fought her long illness, and everyone who saw it will remember her appearance in the House of Commons recently. Our sympathies are with her family at this very difficult time."