Groups are slamming the federal Conservative government's plan to speed up the environmental review process, suggesting it will become a rubber stamp that won't protect the health and safety of Canadians.

"This is about bulldozing things through over the objection of people or without thinking it through," the Sierra Club's John Bennett told CTV's Power Play.

Streamlining the environmental review process was a key plank in the Tories' first majority government budget, released Thursday.

But Bennett, the executive director of the environment watchdog, said the changes will result in weaker environmental assessments, as well as projects being approved without a full understanding of the social, economic and environmental impacts.

"We know we make mistakes and the environmental assessment isn't about stopping projects. It's about making sure that the projects are done properly."

But Finance Minister Jim Flaherty said the budget creates a long-term strategy for job creation, instead of long delays in economic development on projects such as the Northern Gateway pipeline carrying oil from Alberta to the West Coast to feed the hungry Asian market.

"We've had people walk away from projects in this country because of the length of time and uncertainty of environmental reviews," he told CTV's Canada AM Friday.

Reviews need to be done in "a sensible period of time with a deadline" to get the job done, whether it's an approval that could be subject to change or rejection, Flaherty said in an interview from Parliament Hill.

He called the current review process "nonsense" that has dragged some proposals through six to seven years of reviews that have shut the door in some areas of economic development in Canada.

Interim Liberal leader Bob Rae said curtailing the length of time for reviews is fine as long as the process is transparent and has integrity.

But when you have a government that attacks people for appearing before review panels and others being accused of being "environmental terrorists" for speaking up, Rae doubts that can happen, he told CTV's Canada AM Friday.

"I'm not sure this answers the question (that ensures) we have the right balance in place," Rae said from Parliament Hill.

Newly minted NDP Leader Thomas Mulcair said the government has "no intention" of conducting full reviews, suggesting every project will get the green light regardless of public concerns.

"It's not a question of the time one way or another, the question is whether you're going to do a real review and enforce existing legislation, that's the problem," Mulcair told Canada AM in a separate interview.

Mulcair said the government is already bypassing environmental and wildlife laws for oilsands projects.

"That's the problem with the Conservatives, they don't believe in the environment and we're leaving all that to future generations," he said.