"It doesn't get us any further to certainty", he said, and the options of appealing to the Supreme Court or buying into the project should be the last resort.
He's offering few details, however, saying the negotiations will not take place in public.
The Trans Mountain pipeline expansion by the Canadian division of Texas-based Kinder Morgan would dramatically increase the number of oil tankers traveling the shared waters between Canada and Washington state.
If Ottawa was really serious about supporting the Trans Mountain pipeline, it would freeze all discretionary funding to B.C., said Alberta Opposition Leader Jason Kenney criticizing the results of a tri-party meeting Sunday.
"The Trans Mountain pipeline expansion was approved by the National Energy Board in May of 2016 and the Federal Cabinet in November of that year...18 months and no shovels in the ground", he said, adding that due to lack of progress "we need to see a change of government at both the federal and provincial level next year". Horgan defeated Clark in an election past year.
"Ideally, we wouldn't be in this situation right now", Trudeau said.
Although both Horgan and Notley came out of the meeting saying it was collegial and cooperative, neither is coming out of their entrenchments.
Kenney warned new federal legislation can be challenged in court.
It has been a week since Kinder Morgan announced it was halting all non-essential spending on the plan to build a second, bigger pipeline parallel to the existing one between Edmonton and Burnaby, B.C. The company gave the Trudeau government until the end of May to reassure its investors the pipeline would be built, despite mounting opposition. Analysts suggest that could hike gas prices in the Lower Mainland over $2 per litre and would have an immediate, economy-wide impact on the province.
- Legislative options - "We are actively pursuing legislative options that will assert, plus reinforce, the government of Canada's jurisdiction in this matter, which we know we clearly have", Mr Trudeau said.
Trudeau did not specify what form those moves would take, but said Ottawa would be "exerting its constitutional authority" to get the pipeline built. He said whatever financial arrangement is reached will include protections for taxpayers.
"The federal government, along with the government of Alberta, has commenced discussions with Kinder Morgan to establish a financial relationship that will eliminate investor risk", Notley said. "This is a series of discussions that are happening in Calgary, Toronto, Houston and NY".
"I don't think their announcement was entirely arbitrary", he said.
Horgan said he'd received assurances from Trudeau that he would not "punish" British Columbians over their government's objections, meaning Ottawa isn't going to be withholding federal funds from B.C.in an effort to get the Horgan government on side.
"Two weeks ago signing a $4.3 billion infrastructure agreement with the Horgan NDP and now negotiating the $1.3 billion jobs training transfer to the same government in..."
To which Greenpeace responded: "This pipeline isn't going anywhere". "We are simply demonstrating the resolve to actually deliver on that promise to Canadians". The company set a firm deadline of May 31 to have that request fulfilled.
"It has gone through the hoops and, quite frankly, if co-operative federalism means we never, ever, ever make a decision, well I don't think that's a co-operative federalism that Canadians think is in their best interests", she said.
"I'm quite confident that should these discussions end successfully, that the pipeline will be built - and that is good, because the pipeline is in the national interest".
Before Sunday's duelling news conferences were even complete, Conservative Leader Andrew Scheer was front and centre, accusing Trudeau of sitting on his hands for too long and frittering away investor confidence in Canada as a whole.
"His damaging policies ... have only led to more uncertainty and instability in Canada's resource sector", Scheer said.