MP Scott Brison traded his lifelong allegiance to the Progressive Conservative Party for a Liberal membership on Wednesday, saying Paul Martin's vision more closely reflects his own values than the newly merged Conservative Party of Canada.

"I've made my choice. My new political home is the Liberal Party of Canada," Brison, a former Progressive Conservative Party MP told reporters at a joint news conference with Martin.

"I'm interested in playing a role in a centrist, modern political party."

The move across the Commons floor, just days after the Canadian Alliance and Progressive Conservative parties voted to merge, could affect the recent changes to the Canadian political landscape.

Brison, who joined the Tories when he was only 11 years old, refused to criticize the new united conservative party, saying his was a personal decision based on Martin's centrist approach.

"The Liberal Party of Canada under Paul Martin's leadership more closely reflects my values and my vision for Canada than the new conservative party," he said.

However, he did call Harper's response to anti-gay comments, most recently made by MP Larry Spencer "tepid." Spencer was fired from his position as the party's family issues critic for telling a Vancouver newspaper he favoured outlawing homosexuality.

Brison said whenever those comments are made, they help stigmatize a party and he believes that will keep the Canadian Alliance from assuming control of the government.

"Only the political parties that understand the pride that Canadians have of our diversity in this country will ever have the capacity to form a government."

Martin, who will be crowned prime minister on Friday, was beaming with his new catch, saying Brison "will make a tremendous addition to our team." He also welcomed anyone else who might want to join up.

"I want all Canadians to know that the Liberal Party will welcome the talents of any who share our belief in a financially responsible, socially progressive and forward-looking government."

Seated beside his new boss, the member for Kings-Hants was questioned about disparaging remarks he made about then- finance minister Martin.

"He is hesitant, timid, risk adverse. He is highly beatable because he runs from a debate, he does not want to take a stand on anything," Brison said last May.

Brison responded by saying it's all part of the "bloodsport" of politics. "I've said far worse things about members of my former party than I've ever said about Paul Martin," he joked.

As for Brison's former leader, Peter MacKay, the PC chief's suspicions were raised by the timing of the announcement -- days before the new prime minister's cabinet is unveiled.

MacKay racked the defection up to a case of sour grapes and a political move towards a seat at the ministers' table.

And outspoken Tory MP Elsie Wayne said Brison should have given the new party a chance before jumping ship.

"After him being the critic for finance and... condemning the government on so many of their moves, I would have thought that his opportunities would have been far greater with the Conservative Party," Wayne said.

Brison had a good showing in the June campaign for the Tory leadership, but ruled out yesterday running for the leadership of the new Conservative Party of Canada.

Brison is the fourth person to leave the PC caucus, but the first to join the Liberal Party. Former PC Party leader Joe Clark, Quebec MP Andre Bachand and New Brunswick MP John Herron have also severed their ties to the new party.

Clark and Herron will sit as independents in the House of Commons, while Bachand is rumoured to also be considering a jump.

To prevent the Tories from losing official party status, and a parliamentary research budget, four Alliance MPs -- Grant Hill, Deepak Obhrai, James Rajotte and Monte Solberg -- joined the Progressive Conservative Party Wednesday, to boost their caucus total back up to 15 MPs.

In terms of what it means for the new Conservative Party, Manitoba Tory MP Rick Borotsik said the defection speaks to the difficulties the merger has to overcome.

"Perhaps there are greater difficulties than even maybe Mr. Harper and Mr. MacKay had anticipated initially going into these discussions," he said. "I think it doesn't bode well for the new party."

Borotsik said he's prepared to sit in the first new caucus, but is keeping his options open for his future. "I ran as a Progressive Conservative in 1997 and 2000. I don't know what I want to run with in 2004."

Nova Scotia Premier John Hamm said he is disappointed by Brison's move to the Liberal Party, however he doesn't think it will have a negative effect on the provincial Tories overall.

As for Martin's Liberals, they also gained former Bloc Quebecois MP Robert Lanctot in early December.