Political pressure continues to mount on Prime Minister Paul Martin to explain where he and his government stand on the thorny issue of missile defence.

"The Prime Minister is either misleading Canadians or he's misleading himself," NDP Leader Jack Layton told CTV's Question Period on Sunday.

Dan McTeague, the Parliamentary Secretary for Foreign Affairs, said the only way to deal with the issue is to hash it out at the negotiating table rather than dismiss it altogether.

The missile defence issue moved to the top of the political agenda this past week during U.S. President George W. Bush's visit to Ottawa and Halifax.

While he was here, Bush encouraged Canada -- several times -- to sign onto his plan.

"I hope we'll also move forward on ballistic missile defence cooperation, to protect the next generation of Canadians and Americans from the threats we know will arise," Bush said during a speech in Halifax.

"From a sovereignty perspective and (from) all the arguments put forward to why we shouldn't do this, the same argument say why we must be at the table," McTeague said.

Martin said Thursday that the missile defence plan does not necessarily involve the weaponization of space, and Canadian negotiators will continue to press for answers on the issue.

"I have talked to the president about the whole question and the president says it does not imply the weaponization of space,'' Martin told reporters after his weekly cabinet meeting.

One concern being raised is why Bush was pushing so hard on the missile issue during his visit to this country.

"I think that Bush himself decided this is something really important and 'I don't understand these Canadians. And I'm going to make the point, and I'm going to do it'," Globe and Mail reporter Jeff Sallot told Question Period.

Need to get Canada onside?

But Layton wondered if Bush wasn't also trying to get Canada onside in order to shore up opinion elsewhere in the world.

"I think that George Bush wants Canada to be involved here in order to give (the issue) the legitimacy of Canada's voice, which has been traditionally for peace."

Conservative Deputy Leader Peter MacKay said the Prime Minister has to make his position known -- and soon.

"This is really an issue of leadership, MacKay said. "The Prime Minister has been anything but clear."

MacKay agreed with Layton that the best solution is open debate in the House of Commons.

"There has to be an informed debate in Parliament: What are the benefits? What are the costs associated with this?"

McTeague said "its important to refute the myth making that's gone and the hysteria that surrounds this" issue.

He said Canada will have to take a hard look at the issue since it goes to the heart of matters of defence.

"You have 25 minutes for an intercontinental missile to hit Canada," he said. "How do you get a missile to stop it?"

Still, the Liberals are clearly divided on the issue.

Over the weekend, the Quebec wing of the federal Liberal Party has said a resounding 'no' to Canadian participation in a continental missile defence plan.

"I feel there is always a time where we have to take a stand and the Liberals from Quebec took a stand today," Liberal MP Denis Coderre told reporters on Saturday following a policy meeting in Montreal.