Stephen Harper's Conservatives reclaimed a former stronghold in Nova Scotia and stormed a Bloc Quebecois bastion in Quebec, defying polls and a perilous economic climate to win two of four federal byelections Monday.

The Bloc easily hung on to a Montreal-area riding, while the NDP held another in B.C.

The Tories had been widely expected to take back Nova Scotia's Cumberland-Colchester-Musquodoboit Valley. It had been a longtime Tory fortress until Bill Casey -- punted from the Conservative caucus over criticism of the 2007 budget -- captured the riding as an independent in 2008.

With Casey now retired from federal politics, his supporters returned to the Tory fold. Conservative Scott Armstrong took 45.8 per cent of the vote, easily deflecting a challenge from New Democrat Mark Austin, who took 25.7 per cent.

But the Tory win in Montmagny--L'Islet-Kamouraska--Riviere du Loup in Quebec's lower St. Lawrence region was a stunning upset for party that had been written off as all but dead in the province a scant few months ago.

After a nail-biting start in which the lead see-sawed back and forth, Tory Bernard Genereux, a popular local mayor, eventually pulled away from his Bloc rival, Nancy Gagnon. He wound up taking 42.5 per cent to Gagnon's 37.8.

The win gives the Tories their eleventh seat in the province and one of only a handful outside the Quebec City area. It will help cement the Tories' claim to be the federalist alternative to the separatist Bloc outside Montreal.

The Bloc had won the riding in 2008 with 46 per cent of the vote -- 16 points ahead of the Tories.

The NDP was the other big winner of the night, easily hanging on to B.C.'s New Westminster--Coquitlam. With most polls reporting, Fin Donnelly was leading Conservative Diana Dilworth by almost 15 points -- a huge lead in a riding that has produced exceptionally tight races between the two parties in the past.

The NDP could also boast that it managed to replace the Liberals as the second place finisher in Cumberland-Colchester and Hochelaga, an east-end Montreal riding reclaimed for the Bloc by former Parti Quebecois cabinet minister Daniel Paille.

The four contests turned out pretty much as NDP strategists had hoped, allowing them to claim to be the only opposition party with momentum, particularly as compared to the Liberals who finished a distant third in all four races.

"A large segment of the Canadian electorate who for years have been comfortable with the Liberal Party of Canada to represent their values and their point of view in Parliament are slowly but steadily abandoning the Liberal party . . . and more and more are embracing Jack Layton's NDP," said Brad Lavigne, the NDP's national director.

However, the Liberals have not done well in any of the ridings in many years and had set a modest goal of improving their share of the vote over the dismal results gleaned in 2008 under the unpopular leadership of Stephane Dion. They failed to meet even that modest objective in three of the four ridings.

Only in Cumberland--Colchester were the Liberals able to increase their vote share and, even then, only compared to 2008 when Casey's run as an independent sapped the strength of all the parties.

Compared to the 2006 election -- when there was no popular independent to skew the results -- the Tories are down about six percentage points and the Liberals are down two points, enough to cede second place to the NDP, which increased its vote share by about six points.

The two wins boost the Conservatives to 145 seats in the House of Commons, while the Liberals remain at 77. The Bloc is at 48 and the NDP at 37, with one Independent.

Conservative party spokesman Fred DeLorey said the results demonstrate Canadians approve of the government's efforts to help Canada weather the global economic recession. And he claimed they represent an indictment of Michael Ignatieff's leadership of the Liberals.

"What kind of official Opposition party hoping to win government does not do well in byelections in the midst of a global economic downturn? One that's in trouble," DeLorey said.

A Liberal party spokesperson was not immediately available.

But earlier Monday, the party issued talking points arguing that the byelections were actually a referendum on Prime Minister Harper's leadership.

"If the Conservatives fail to win all of the seats in tonight's byelections, it will be a signal that Canadians are still not willing to turn over the keys to such a partisan and incompetent government," the party maintained.

The media lines went on to argue that Liberals have not held the four ridings "in 30, 40 50 years" whereas Conservatives "have held all four in recent memory."

In fact, the Liberals won Cumberland-Colchester in 1993. And they won what is now a big chunk of New Westminster-Coquitlam in 1997.