Vote-splitting in one riding and a popular candidate in the other gave the B.C. NDP two big byelection victories in former Liberal strongholds.

The New Democrats' Gwen O'Mahony, who has run twice unsuccessfully, came up the middle in Chilliwack-Hope with about 41 per cent of the popular vote Thursday night.

Laurie Throness from the Liberals and John Martin of the B.C. Conservative Party shared about 58 per cent, fulfilling Clark's warning about splitting the "free enterprise" vote.

In Port Moody-Coquitlam, the NDP's Joe Trasolini captured about 54 per cent of the vote, well ahead of the Liberals' Dennis Marsden with 30 per cent and the Conservatives' Christine Clarke with 15 per cent.

A former mayor of Port Moody, Trasolini was seen as the front-runner.

"This is going to send a clear message, the NDP is growing," said NDP Leader Adrian Dix on Thursday.

Premier lowered expectations

Both NDP victories came in ridings that the Liberals won easily in the last three provincial elections.

"It gives credence to Adrian Dix's claim that he's regarding all seats as winnable," said Michael Prince, a political scientist and social policy professor at the University of Victoria.

"He was heightening and raising expectations, while premier was all about lowering expectations," said Prince.

Clark played down the significance of the byelections, noting most don't tend to go the government's way, no matter what party is in power in B.C.

In the leadup to Thursday's vote, the premier reminded British Columbians about how that kind of vote division elected former NDP premiers Mike Harcourt and Glen Clark.

"If you vote to split the free enterprise vote, all you're going to do is elect Adrian Dix the premier of B.C., and not for one term, probably two," she said on Wednesday.

Some business leaders who support the Liberals have been calling on Clark to form a political merger with the Conservatives to prevent an NDP victory in the May 2013 provincial election.

Call for centre-right to unite

Thursday's byelection results mirror recent polls that found the Liberals and Conservatives battling for second place behind the New Democrats.

 "[Conservative Leader] John Cummins has enabled the NDP to win in this riding tonight," said Liberal MLA John Les, calling for the centre-right to come together. "If you’re not a socialist, there’s nothing to be satisfied with here tonight."

He continued: "All parties on the centre right have to carefully consider the greater provincial good ahead of the specific good of any individual or party."

But Cummins said he was satisfied with his party’s improved byelection results from the last provincial vote.

"It says to me that we're on the uptick and the Liberals are on the down," said Conservative Leader John Cummins on Thursday, dismissing any merger with the Liberals.

"People have abandoned the Liberals in droves and that's the message here tonight."

But political scientist Prince believes the "humbling" third-place finishes now make it difficult for the Conservatives to attract the strong candidates they need to be a factor in the general election.

On the other hand, Prince said the NDP wins can only help the party attract more candidates like Trasolini. The popular ex-mayor was a B.C. Liberal and had worked on Premier Clark's MLA campaign in 1995.

Both ridings were vacated by their Liberal MLAs last August when Iain Black stepped down in Port Moody and former attorney general Barry Penner quit to spend more time with his wife and baby daughter. 

With files from the CBC's Miyoung Lee and the Canadian Press