Ontario will hold its election on Oct. 6. Premier Dalton McGuinty, who is trailing the Progressive Conservatives in the polls, will have a difficult time getting a third mandate for his Liberal government (though a new poll suggests he’s narrowing the gap with PC Leader Tim Hudak).

The New Democrats under Andrea Horwath, meanwhile, will try to capitalize on their federal counterparts’ success, further squeezing the Liberal leader.

Here are some of the ridings to watch on election night in Ontario:

Barrie: Aileen Carroll, who has served in the cabinets of both Paul Martin and Dalton McGuinty, will not be running for re-election. Karl Walsh will be running for the Liberals while Rod Jackson, a former city councilor, will be the Tory candidate. The riding was won by only three points in 2007.

Eglinton-Lawrence: With a five-point margin in the last election, this riding was already one to keep an eye on. But Rocco Rossi, former National Director of the Liberal Party of Canada and Toronto mayoral candidate, has made it even hotter as he is running for the Tories in a bid to unseat Liberal MPP Mike Colle, who has sat at Queen’s Park since 1995.

Davenport: With 42 per cent of the vote to the NDP’s 37 per cent, this was a close riding in 2007. But without a Liberal incumbent, and with the federal New Democrats winning the riding by a 26-point margin in the recent federal election, this Toronto-area seat could flip to the NDP provincially.

Don Valley West: Kathleen Wynne, Minister of Transportation, won this riding with 50 per cent of the vote in 2007. Andrea Mandel-Campbell, a former journalist, will try to take it from her for the PCs. The federal Conservatives beat out the Liberals in this riding in May with 43 per cent of the vote to 42 per cent. It could be a close one provincially as well.

Hamilton Mountain: Held by the Liberals since 1999, Sophia Aggelonitis, Minister of Revenue and Minister Responsible for Seniors, beat out the NDP by only three points in 2007. In May’s federal election, the Liberals finished in third with just 16 per cent in this riding. The New Democrats won it with 47 per cent.

Ottawa West-Nepean: Bob Chiarelli, former mayor of Ottawa, won the riding for the Liberals in a 2010 by-election, but placed only four points ahead of the Tories. The PCs will be putting up Randall Denley, former municipal affairs columnist for the Ottawa Citizen, making this riding the one to watch in the national capital.

Stormont-Dundas-South Glengarry: Mark MacDonald of the Liberals will try to hold on to his seat after the departure of Jim Brownell. The Liberals took this seat by 10 points in 2007, but it was a Conservative landslide federally.

Thunder Bay-Superior North: If the New Democrats are to challenge for the role of the Official Opposition, seats like this one need to turn orange. Michael Gravelle, Minister of Northern Development, Mines and Forestry, won the riding with 47 per cent of the vote in 2007 and has held it since 1995 for the Liberals. But federally, the NDP won this riding with 50 per cent of the vote, 33 points ahead of the Liberals.

Timiskaming-Cochrane: David Ramsay, the Liberal MPP who has held this northern Ontario riding since the 1980s, will not be running for re-election. Denis Bonin, a former municipal councilor, will be flying the Liberal banner. With only two points separating the Liberals from the New Democrats in the 2007 election, the Liberals may have a hard time holding on.

Vaughan: Formerly a safe Liberal riding both federally and provincially, Vaughan flipped to the Conservatives federally in last year’s high-profile by-election that sent Julian Fantino to Ottawa. He just beat out Liberal candidate Tony Genco in that race. This time, Genco will be running for the Progressive Conservatives. Though Liberal incumbent Greg Sorbara won with 62 per cent of the vote in 2007, a dramatic shift in support is not unthinkable in this GTA riding.

Éric Grenier taps The Pulse of federal and regional politics for Huffington Post Canada readers on Tuesdays and Fridays. Grenier is the author of ThreeHundredEight.com, covering Canadian politics, polls and electoral projections.