TORONTO - Premier Dalton McGuinty's government has a lot riding on Thursday's byelection in Toronto Centre, a seat the Liberals have held for a decade but one the opposition parties feel they can win by tapping perceived voter anger over the harmonized sales tax.

However, merging the provincial sales tax with the GST was on the minds of voters in September during the last byelection, in neighbouring St. Paul's, and the Liberals were able to easily hang onto that riding, noted McGuinty.

"I think it's an issue -- how could it not be -- but it was an issue in the byelection before that as well," he said.

"I think (voters) may have noticed that effective the first of this month, they all got a tax cut."

Toronto Centre has one of the most ethnically and economically diverse populations in the country, from the Victorian townhouses of Cabbagetown and the mansions of Rosedale to the public housing of Regent Park and the soaring apartment towers of St. Jamestown, home to wave after wave of new immigrants.

The riding, with almost 115,000 people, also includes upscale Moore Park, the downtown shopping core, highrise condominiums along Yonge St. down to Lake Ontario, the still-being-reclaimed Distillery District, the gay village and even the Ontario legislature itself.

Liberal candidate Glen Murray, 52, the former mayor of Winnipeg, is talked about as a potential cabinet minister, and has inherited the well organized riding association from former deputy premier George Smitherman, now a candidate for mayor of Toronto.

Murray, who says he "fell in love with a guy from Toronto," plays down the fact he's only lived in the city for about five years.

"Half the people in this community weren't born here," he said. "The very success of Toronto is that it is a magnet for people."

In addition to volunteering for Toronto's first gay street patrol in the 1980s and heading the Canadian Urban Institute, Murray -- Canada's first openly gay mayor -- has also been campaigning for affordable housing, advocating a "key in every pocket" so people have somewhere safe to go off the streets.

"If you don't have a safe home, it's hard to have dignity, it's hard to have a job, it's hard to participate in society," he said.

For NDP candidate Cathy Crowe, a well-known street nurse who spent decades tending to the poor and homeless, it was the wasteful spending and inadequate social funding of the Liberals that pushed her to run in the byelection.

Crowe, who has a daughter and two grandchildren, formed the Toronto Disaster Relief Committee, which declared homelessness a national disaster 11 years ago, thinking social injustice had reached a low-point under then premier Mike Harris. But things got even worse under the Liberals, said Crowe.

"There are a lot of emergencies in the riding that built up over the last year in the recession, and it just became apparent to me that a lot of those issues were worsened during the Liberal McGuinty government," she said. "Some of them have been created by the previous government, but they have been severely worsened."

Progressive Conservative candidate Pam Taylor, a lawyer with her own practice, is running in Toronto Centre for the second time, having finished a distant second to Smitherman in 2007. Taylor said she's essentially been campaigning non-stop since then, and jokingly describes herself as the politician who hasn't gone away.

"There were a lot of people here who've been left behind by the McGuinty government," said Taylor. "The recession has hit a lot of people here very hard and I spent a lot of time working with them, and I'd like to take that further to government so I can actually help in a way that I'm not able to do as an individual."

Taylor has reduced her legal practice to allow her to also focus on community activism, working with lower income residents and immigrants in St. Jamestown. The pending HST has made the Liberals less popular with voters, she said.

"The prospect of adding eight per cent to all of the services that are consumed is, to most people, something that's quite frightening," said Taylor.

Taylor, who is married with two sons in their early 20s, calls Murray a "parachute" candidate, and said she's willing to stack her community service in the riding up against Crowe's work with the homeless.

Stefan Premdas, 32, described as a job creation and employment specialist, is running in Toronto Centre for the Green Party of Ontario, which does not have any seats in the legislature. Premdas immigrated to Canada as a young boy from Trinidad and Tobago and previously worked at the South Riverdale Community Health Centre.