Liberal Leader Michael Ignatieff says that if an election is called in the coming months, his party is the only true alternative to the Conservatives.

In an interview with CTV's Question Period, Ignatieff says that a vote for Jack Layton's NDP or Gilles Duceppes' Bloc Quebecois is essentially a vote for another Conservative government.

"What I'm saying is, it's time for Canadians to make a choice between two governing parties," Ignatieff said.

In particular, Ignatieff said that he and Prime Minister Stephen Harper are at odds over major issues, such as building new jails and purchasing new F-35 fighter jets.

"Their priorities and ours are not the same," he noted.

"I'm trying to create that big, broad tent in the centre and represent a clear alternative to Mr. Harper," said Ignatieff, adding, "We put our emphasis squarely on the middle-class family."

However, when asked if the Liberals will vote in support of the Conservative budget in the coming session, Ignatieff said he cannot make a decision without first seeing the document.

"Let me read the thing first. I'm not like Mr. Layton, who votes for things before he's even read it," Ignatieff said, taking a shot at his NDP rival for saying that he would vote down the government's stimulus plan even before it had been tabled.

But Ignatieff definitively said that he would be prepared to vote down the budget and topple the government if the legislation doesn't mesh with what's good for the country.

"We're a party that's out there to present a clear alternative to the Conservatives, and I think we've had a good year, on the F-35, on government waste, on the G20 -- on issue after issue."

When discussing potential election issues, such as a deal between Ottawa and Washington to create a continental "security perimeter," Ignatieff accused the prime minister of being secretive and opaque.

But when Question Period host Craig Oliver suggested that Harper is perhaps attempting a pre-election gambit to create a wedge issue on security, Ignatieff was unperturbed.

"I'm not going to be set up by anybody, least of all Stephen Harper," said Ignatieff, who noted that he isn't opposed to the security perimeter.

"The issue is Mr. Harper doing secret negotiations with the Obama administration and not telling us what's in play. Are our Charter rights at risk? Is control of our immigration policy at risk? Are there sovereignty implications here?"

"We will fight him on the issue of secrecy in this deal," the Liberal leader said.

On other key policy questions, Ignatieff said his party has been out in front of the government and offered Canadians leadership rather than reactionary criticism.

In particular, he said that championing a post-combat training mission in Afghanistan past the 2011 deadline was particularly important, since the Harper government hadn't taken a firm stand.

"My sense of the story is, we took leadership as a party, and I think we did the right thing."

During the conversation, Ignatieff also spoke about his personal experience as opposition leader.

Since leaving a prestigious post at Harvard to enter the scrappy political scene in Ottawa, the Conservatives have attempted to brand Ignatieff as being a selfish academic.

But the Liberal leader said he has worked hard recently to combat the negative attacks, and this summer he spent weeks travelling the country by bus and meeting with supporters and non-supporters alike.

"I think I had a sense of learning how to be the kind of politician that establishes trust, because I'm willing to listen to people," Ignatieff said of his summer tour.

"I had a great sense of closeness and contact."