Labour had a majority of more than 5,000 at the last election

Mike Watson resigned earlier this month after being found guilty of wilful fire-raising at an Edinburgh hotel.

Launching his campaign, Charlie Gordon said Watson deserved to be punished but voters were still behind the party.

Nationalist hopeful Maire Whitehead and Tory candidate Richard Cook began their campaigns with a big focus on health.

Watson, who held a majority of 5,112 over the SNP in the 2003 Scottish parliamentary election, is due to be sentenced on 22 September, seven days before the by-election.

Former Glasgow City Council leader Mr Gordon said voters understood that only the disgraced peer was to blame.

CATHCART CANDIDATES Charles Gordon - Labour Maire Whitehead - SNP Arthur Sanderson - Lib Dem Richard Cook - Scottish Tories Ronnie Stevenson - SSP Pat Lally - Independent Chloe Stewart - Scottish Greens

He said: "Mike Watson has to pay for what he did and I don't think he should return to his seat in the House of Lords.

"But people on the doorstep are telling me they understand it wasn't the Labour Party who let them down, it was one man."

Flanked by First Minister Jack McConnell and Parliamentar Minister Margaret Curran, he also dismissed reports that Mr McConnell had favoured restaurateur Charan Gill as candidate.

"Cathcart Labour Party chose the candidate and I'm the candidate they chose," he said.

Reporters went on to quiz him about his no-nonsense rhetorical style.

Reference was made to an article in which he was disparaging about New Labour and was also quoted as saying: "I was going to say 'Jack's a pragmatist' - but that's to impute to Jack a degree of sophistication."

'Unfair council tax'

Mr Gordon said: "People talk about my old-fashioned debating style but I did not come into political life to conduct debates but to do things for people."

Nationalist candidate Maire Whitehead said voters were "sick" of empty promises from Labour.

She said: "The SNP has been unwavering in its support for retaining and improving services at the Victoria Infirmary. SNP success can make a difference and secure the future of local health services.

"A vote for the SNP is a vote to scrap the unfair council tax, which in Glasgow is 11% higher than the Scottish average. It has gone up 50% since Labour came to power."

Conservative candidate Mr Cook, who fought Cathcart in the 2001 and the 2003 elections, said: "The people of Cathcart deserve an MSP who will stand up and speak out for them and if elected I promise to be their local champion.

"For example, I will not give up the fight to retain accident and emergency services at the Victoria Infirmary, a battle that only the Scottish Conservatives are willing to take to the failing Labour/LibDem executive."