OTTAWA -- Alberta Premier Jason Kenney is warning that if a federal bill overhauling environmental assessments passes in its current form, it will threaten Canadian unity and there will be "an immediate constitutional challenge."

Kenney testified to the Senate's energy committee Thursday morning about Bill C-69 -- what he calls the "no more pipelines" bill -- saying it flagrantly violates Alberta's constitutional right to regulate its natural resources.

The legislation establishes a new process for reviewing major projects with a national scope or in federal jurisdiction. The federal Liberals say it is needed to restore confidence in the assessment process and finally get big projects built; critics say it gives too much political power to the federal cabinet to interfere and allows too much involvement of lobby groups that might not have any direct connection to a proposed project.

Kenney wants all the amendments proposed by the former NDP government in Alberta accepted, including a hard two-year timeline for the whole process, less room for interference by federal ministers, and an exemption for in-situ oil sands projects in Alberta that are currently reviewed by the Alberta Energy Regulator. Similar amendments have been requested by industry associations, including the Canadian Association of Petroleum Producers and the Canadian Energy Pipeline Association.

All of them, including Kenney, said the amendments have to be made as a package.

"This bill does not need a nip and tuck," Kenney told senators. "It needs major reconstructive surgery or it needs to be put out to pasture."

Three federal ministers behind the bill spoke at the committee following Kenney: Environment Minister Catherine McKenna, Natural Resources Minister Amarjeet Sohi and Transport Minister Marc Garneau.

They implored the senators to remember that the existing system has failed to allow a single new pipeline built to either of Canada's coasts, and has resulted in multiple legal challenges. The goal of C-69, they said, is to prevent those kinds of delays.

Sohi told senators the Trans Mountain pipeline expansion was proposed in 2013, yet six years later the government is still responding to court cases that have thus far kept shovels out of the ground.

Sohi said the government wants to get good projects built with sound environmental protections. He said while the government is open to amendments, it is not open to wiping out the bill's attempt to address the environmental and Indigenous consultation requirements that have led to most of the court challenges.

"The process must look after the environment," Sohi said.

But Kenney said the government is putting national unity at risk by trying to get this bill adopted. He pointed repeatedly to a recent poll suggests half of Albertans are prepared to secede from Canada.

He said he thinks most people are just "blowing off steam" to express frustration, but contends that if support for seceding in Quebec were at 50 per cent, no federal government would try to pass a bill causing so much anger.

"I'm simply pointing out there is a deep and growing frustration in my province. it's the role of the PM of any party to safeguard national unity," Kenney told reporters following his Senate appearance. "These bills undermine national unity."

Sohi, an Edmonton MP, said after his own committee appearance that he knows the anxieties Alberta families are facing because of the economy. But he said he rarely hears anyone threaten to leave Canada.

"I think it is irresponsible for anyone to suggest that Alberta will leave the confederation," Sohi said. "Yes we have challenges and we are working hard to address those challenges."

Later Thursday, Kenney is to meet face-to-face with Prime Minister Justin Trudeau, the political foe he used to face as a Conservative MP and attacked relentlessly in his successful bid to become Alberta's premier.