OTTAWA - Liberal MPs got a short but pointed lecture Wednesday about the havoc loose lips can wreak on a political party and its leader as they continue to languish in opinion polls.

Sudbury MP Diane Marleau went to the microphone during a closed-door caucus meeting and, according to insiders, asked all those who wanted to lose the next election to raise their hands. Not one hand went up.

"If that's the case," Marleau reportedly said, "you all need to shut ... up."

After a brief silence, the assembled MPs and senators gave Marleau a standing ovation.

Her terse tongue-lashing followed several weeks of griping from mostly anonymous Liberals about their novice leader, Stephane Dion. The grumblers have questioned Dion's political skills, his judgment in entering into a non-compete agreement with Green Leader Elizabeth May, his choice of staff, and stagnant poll numbers.

Marleau's intervention highlights the symbiotic relationship between polls and internal sniping. The more the party's support level drops, the more party members are inclined to carp to the media about their leader, generating negative stories and a sense of crisis that helps produce yet worse poll numbers.

The latest Decima poll contains good news and bad news for the Grits. The survey suggests Prime Minister Stephen Harper's Conservatives dropped to 30 per cent nationally - a virtual tie with the Liberals.

But the Grits remained stalled at 29 per cent nationally and support in the party's remaining bastion, Toronto, has eroded significantly since Dion was elected leader Dec. 2.

At the time of Dion's ascension to the Liberal throne, Decima found the Grits held a massive lead over all other parties in the Toronto area - a four-week average of 60 per cent compared to 17 per cent for the Tories and 12 per cent for the NDP.

The most recent four-week average found the Grits' lead reduced by half. Their support in Toronto stood at 44 per cent, compared to 25 per cent for the NDP and 24 per cent for the Tories.

Among urban voters in general, once a Liberal strength, the Grits and Tories continued to hover at 30 per cent while the NDP climbed several points to 19 per cent.

Decima CEO Bruce Anderson said the Liberals' choice of leader appears to have started the rise in NDP support and the erosion of the Liberals' Toronto fortress.

"It's hard for me to see what in these times would be driving votes to the NDP," he said.

"Instead, I go to the (question) if they're moving away from the Conservatives and they're not stopping at the Liberals, is it something about the Liberals that's keeping that from happening?

"And when you look at the trend lines in 416 and you say really this movement can be traced back to the time when they changed leaders, I think there's a reasonable story there."

Anderson said the results are a wake-up call for Liberals; they're still competitive but they have a lot of work to do to shake loose Tory votes and keep them from drifting to the NDP.

The margin of error for the national survey results, based on a sample of just more than 1,000 Canadians, is 3.1 percentage points, 19 times in 20. The margin is larger for the smaller Toronto sample: six percentage points 19 times in 20 for the four-week averages.