OTTAWA — George W. Bush scolded Conservative Leader Stephen Harper for his silence on missile defence and asked him to help secure Canadian involvement in the U.S. plan, The Canadian Press has learned.

The U.S. president used his trip to Canada late last year to bluntly voice irritation with Harper's enigmatic position on missile defence, sources on both sides of the border say.

One U.S. official described Bush's reproach to Harper as: "Please don't play partisan politics with this.''

"I would hope you're looking at this in Canada's national interest and not in terms of partisan politics,'' Bush reportedly told Harper.

Recent polls have shown a majority of Canadians oppose Canada's participation in missile defence.

That opposition has mounted in the vacuum of any vocal support for the program from anyone in the Liberal government apart from Defence Minister Bill Graham and Public Safety Minister Anne McLellan.

Prime Minister Paul Martin supported Canadian involvement in the initiative when he was a leadership candidate, but has avoided moving forward without Conservative support.

Bush unexpectedly asked Martin pointed questions about Canada's refusal to sign during their meeting, but it's now clear the prime minister wasn't the only Canadian political leader to get the Bush treatment.

Harper didn't deny being pressured by Bush last Nov. 30 during their half-hour meeting. But he said it appeared someone had misled the president about Conservative policy.

"It was clear to me at the outset of our conversation that the president had been misinformed about our position,'' Harper said in an interview.

That position, Harper replied, is not hostile to missile defence. But it will force the Liberals to properly explain the plan before bringing it to Parliament.

"We're not going to agree to a proposal we don't have the details for,'' Harper said.

"While we're all very open in the Conservative party to this kind of initiative we don't really trust the Liberals to just negotiate with a blank cheque.''

Another Conservative offered a far blunter explanation for why a military-friendly and staunchly pro-U.S. Official Opposition is suddenly mute on missile defence: it makes Liberals sweat.

"Let's see them govern and make a decision for once, instead of relying on us.''

Now two party leaders who previously supported missile defence -- Harper and Martin -- are entangled in a cautious dance with nobody's feet moving and everyone's eyes glued to public opinion.

The Liberals are frozen at the thought of being forced to fight a future election campaign as the only federal party officially in support of the missile project.

Polls suggest the program is supported by only about one-third of Canadians, and is especially unpopular with key electoral constituencies: Quebecers, urban, and female voters are especially hostile to the plan.

The controversial project has also divided the governing party and is expected to overshadow the Liberal policy convention next month in Ottawa. The party's youth and Quebec wings plan to table motions against BMD.

"We know we're going to get destroyed (on missile defence) at the convention,'' said one senior Liberal.

That kind of hostility had Liberal brass hoping they could use the Conservatives to carry a symbolic vote on missile defence in the House of Commons.

With the support of his foes, the prime minister could then sign on to missile defence shielded against attacks from rivals, especially from Harper.

Martin has been frustrated by Harper's refusal to play along _ so frustrated that during his own meeting with Bush, the prime minister tried blaming his opponent for the missile defence standstill, according to one account.

One of Bush's interlocuters said Martin told the U.S. president he had shown Harper a "proposal'' for missile defence that the Conservative leader refused to support.

Conservatives say they were told of Martin's complaint to Bush. They say Harper has seen no formal proposal and are accusing the prime minister of misleading the president.

But the decision to raise missile defence with Harper was made weeks in advance and had nothing to do with anything Martin said, according to U.S. officials.

"The president might not be following Canada that closely -- but there are people (in Ottawa) and in Washington paid to do that,'' said one U.S. official.

"The president was getting his information from U.S. sources. . . (And) there was concern.''