The federal Conservatives are defending their plan to force striking Canadian Pacific Railway employees back to work as a way to keep the economy on track, while the union representing 4,800 workers says their collective bargaining rights are under attack.

Labour Minister Lisa Raitt, flanked by four other cabinet ministers, on Monday made her case based on a need to keep the trains running so other businesses can keep their products moving.

Industry Minister Christian Paradis argued there's between $30 million to $50 million a day in lost productivity and expenses because of the work stoppage.

"Canada’s manufacturing sector is an extensive web of interconnected companies that allows for just-in-time delivery of components and finished products. A disruption in the supply network would affect every company in the chain," he said.

The railway is Canada's backbone and links the country with major U.S. industrial centres, Raitt said in a speech to the House of Commons, and the work stoppage is affecting Canada's reputation.

"We're only one link in a long supply chain. What happens here affects inbound and outbound traffic," she said. "We cannot afford to be that weak link."

Raitt said she wants to see CP trains rolling on Thursday, or earlier if the two sides get back to the table. The back-to-work legislation would send the union members back to their jobs, extend the current agreement until the two sides reach a new one, and provide for arbitration to find a deal within 90 days of the government appointing an arbitrator.

With pensions one of the major issues to be resolved, Raitt was asked whether her legislation showed she was on the side of shareholders.

"That’s absolutely ridiculous. I work for the Canadian public and the national economy," she said.

Collective bargaining 'under attack'

The union, which represents more than 4,800 Canadian Pacific workers, says management isn't bargaining with striking workers because the federal government announced it would bring in back-to-work legislation.

The union spoke to the media as the government introduced a motion to limit debate on the legislation in the House of Commons just after noon in Ottawa. The legislation itself was introduced just after 3 p.m. ET.

Doug Finnson, the union's chief negotiator, says it's only because the government said it would act that CP management isn't at the table.

"Collective bargaining in this country is under attack, certainly," he said.

"As long as the government intervenes in collective bargaining, and in my opinion, unfairly favours the employer, the employers are going to simply line up, every one of them … knowing that the government's going to intervene, suspend collective bargaining artificially, and get into this return-to-work legislation, which from what I understand in the past two experiences, has significantly favoured the employer," Finnson said, referring to legislation that forced Canada Post and Air Canada workers back to work.

In the case of Canada Post, management had locked out workers after 11 days of rolling strikes. The legislation imposed a final offer selection process to resolve the dispute.

Raitt said the government isn't to blame if the union and management at CP couldn't reach a deal. The two sides have an obligation to reach a deal, she said.

"It may seem to be very nice and easy to come to Parliament. [Management] are not going to get the legislation they expect or they want in either case, and secondly, it doesn’t help them in their business plan moving forward," Raitt told Evan Solomon, host of CBC's Power & Politics.

"The overall message to employers is: don’t come to the government for legislation. We don’t want to do this. We don’t want to have to intervene at all, and yet when the national economy ends up being affected, we have no choice but to intervene."

Pensions a major issue

The Teamsters union says pensions are one of the major sticking points in the talks. That's ironic, Finnson said, because two of the biggest shareholders in CP are the Ontario Teachers Pension Plan and the Canada Pension Plan, which are pension funds.

"Isn't that a little ironic that the workers at CP Rail are being asked to give up the value of their pension plan, and indirectly it's going to benefit two other pension plans in Canada?" Finnson said.

If it passes, the union won't disobey the law, Finnson said, which doesn't seem to have some of the measures that other back-to-work bills have contained.

The union has to take a closer look at the measures, he said.

A statement by CP says it will co-operate with any decision of Parliament.

"Once the legislative process unfolds, our company will shift our attention to fully preparing for a timely and disciplined ramp-up in operations with a view to achieve full production levels as soon as possible for the benefit of all our customers," Ed Greenberg, a spokesman for CP, said.

'Takes a lot more pressure' off employer

Opposition  MPs said earlier in the day that the Conservative government took away any incentive for CP management to bargain when it announced it would introduce back-to-work legislation if talks didn't yield an agreement.

Raitt made the announcement last Wednesday, less than 12 hours after the Teamsters Canada Rail Conference started the strike and while the parties were still negotiating.

Talks broke off Sunday between the rail company and the union representing 4,800 striking locomotive engineers and conductors.

NDP finance critic Peggy Nash, a former union negotiator, says announcing the government is prepared to intervene makes resolving the strike through negotiations much more difficult.

"If I'm the employer, I'm thinking it takes a lot more pressure off of me to not have to negotiate a settlement," Nash said.

NDP Leader Tom Mulcair met with the union Monday morning in his office.

Management in labour disputes perceives arbitration will be to its advantage, Liberal House leader Marc Garneau said.

"This government sends that signal constantly to the private sector. We saw what they did with Canada Post, we saw what they did with Air Canada, and it's the approach of the government that is hostile to negotiations with the unions."

The government is moving to limit debate on the motion, providing two hours of debate in the House, plus an hour for study at committee of the whole, where all MPs can ask questions, followed by 30 minutes for the final reading in the House. Under the motion, the bill would trump all other business in front of the House, and only cabinet ministers would be allowed to propose votes during the debate.

MPs will vote on the motion to apply time allocation Tuesday night. The government could bring the back-to-work legislation forward for debate and voting after 8 p.m. on Tuesday night, with the final vote to be held when it concludes.