Liberal MP Wajid Khan has crossed the floor and joined the Conservatives, meaning Prime Minister Stephen Harper can push for a majority vote with the help of Jack Layton's NDP.

The Conservatives now have 125 of 308 seats in the House of Commons.

"The combination of the Conservatives and the NDP (29 seats) gives you 154 seats -- a majority you need," reported CTV's David Akin. House Speaker Peter Milliken - a Liberal -- does not vote.

"This makes Jack Layton and the NDP much more important."

Harper announced the defection Friday in Ottawa.

"We have built a party that welcomes all Canadians," said Harper. "That's why I'm proud to announce that Wajid Khan, the representative from Mississauga-Streetsville, is joining the Conservative caucus."

Harper said Khan put Canada before his party after the alleged terrorism arrests in Toronto last year when he offered to help the Conservatives.

Harper then named Khan, a former fighter pilot in the Pakistani military, as his adviser on the Middle East and Afghanistan during last summer's Mideast crisis between Israel and Lebanon.

"He will continue as my advisor on issues related to the Middle East and Central Asia," Harper said Friday.

Khan said the Conservatives' commitment to new Canadians helped influence his decision.

"I have noticed that more and more Canadians are excited about joining the Conservative party... I came to the conclusion that my ideals and priorities and those of my constituents would be better served in the Conservative party," Khan said Friday, alongside the Prime Minister.

"I was very pleased when Prime Minister Harper agreed that I should join Canada's new government."

Khan said his former Liberal party was at odds with his values.

"Quite frankly, the Liberal party has moved away from people like me -- people who believe in free enterprise, support for families and a stronger, more assertive Canada on the world stage."

Khan said he informed Liberal Leader Stephane Dion of his decision on Friday.

"I respect Mr. Dion but I feel that Canada needs a leader and that leader is Prime Minister Stephen Harper."

Dion had told Khan to choose between his party and the Conservatives.

He said Khan could not continue serving as Harper's 'special adviser' and remain a Liberal.

"It is with regret that I have received word of Mr. Khan's decision to leave the Liberal Caucus and join the Conservative Party," Dion said Friday.

"As a member of the Liberal Party of Canada, I was never comfortable with Mr. Khan serving as an advisor to a Conservative Prime Minister, as Mr. Khan has done since August of last year. As Leader of the Party, I felt it imperative that he decide to which party he would ultimately be loyal. Mr. Khan has now made that decision."

Khan said Dion's public ultimatum forced him to make a decision.

"When I'm given a choice to choose between a political party and my country, I will always choose Canada."

On Thursday, Harper unveiled a newly expanded cabinet and moved Rona Ambrose out of her environment portfolio in an attempt to recover political ground lost in the debate on climate change.

In all, five new junior cabinet positions were created and eight ministers took on new roles or switched posts as Harper moved to overhaul his minority government with the threat of a looming spring election.

Khan, 60, emigrated to Canada in 1974 and was a successful businessman in Toronto before entering politics.