The Conservative government says it won't take "marching orders from union bosses" as it defends controversial legislation that gives cabinet new powers over spending at independent Crown corporations.

Opposition parties are voicing strong opposition to measures in the latest budget implementation bill after Treasury Board President Tony Clement said they would be used to "key in on" some Crown corporations more than others. He specifically listed Canada Post, the CBC and Via Rail.

On Wednesday morning following a Conservative caucus meeting, both Mr. Clement and Finance Minister Jim Flaherty declined to answer questions from reporters. Instead the government position was expressed by Parliamentary Secretary Pierre Poilievre, an MP Prime Minister Stephen Harper often relies on to stir controversy and speak for the government on hot files.

Story continues below advertisement

"I am not here to take marching orders from union bosses," said Mr. Poilievre. "I represent taxpayers and frankly taxpayers expect us to keep costs under control so that we can keep taxes down. It is for those taxpayers that we work. Not union bosses."

Mr. Poilievre specifically defended the budget bill measures, which would give cabinet the power to issue orders to Crown corporations that lay out the terms for pay, benefits and other labour relations issues with both unionized and non-unionized staff. The bill would also create a new rule that would allow a government official from Treasury Board to sit in on collective bargaining negotiations at Crown corporations.

The government said in the 2013 budget that it wants Crown corporations to move to a 50/50 cost sharing arrangement between employees and employers for pensions. It also wants retirement ages at Crown corporations to be aligned with recent changes in the core public service.

"Any liabilities from a Crown corporation are passed on to taxpayers. We are the representatives of Canada's taxpayers and we have a responsibility to ensure that those Crown corporations live within their means and that the costs are kept affordable to Canadian taxpayers," he said. "Our focus is on low tax, low-spending government that eliminates the deficit on time and on schedule and this is part of the package to make that happen."

Both NDP Leader Thomas Mulcair and Liberal Leader Justin Trudeau spoke out against the proposed new powers, arguing they go against the basic principle of Crown corporations in that they are supposed to be independent of the government of the day.

"Today's International Workers Day. This is the gift from the Conservative government. Another example of downward pressure on working conditions and salaries," said Mr. Mulcair.

"They can't have it both ways," he said. "Either they're Crown corporations and they're autonomous and they're allowed to negotiate and set things on their own, or they're not... This is public money. We've decided that an arm's length situation is the best. Every time you ask them about a Crown corporation they say it's arm's length. We have nothing to do with that. But now they're proving just the opposite."

Story continues below advertisement

Mr. Trudeau described the changes as "very troubling" and expressed concern about what the new powers might mean for cultural and scientific organizations.

"The fact that this government is so heavy-handed in its approach to unions, to collective bargaining means that I think this is a recipe for political interference in what should be arm's length agencies and it is a concern to me," he said.

The national actors union ACTRA released a strongly worded statement Wednesday condemning what it described as the "Conservative government's assault on CBC's collective bargaining and journalistic independence."

The union represents 22,000 professional performers and negotiates on their behalf with the CBC.

"We have a 70-year history of collective bargaining with the CBC," said ACTRA National Executive Director Stephen Waddell in a statement. "These are never easy negotiations for either side, but we find agreement and address the needs of both sides. There is no good reason and no place for this kind of intrusion into our collective bargaining. Furthermore, the intervention of government into the decision-making of the public broadcaster threatens journalistic independence and could affect content decisions at the CBC."