MINNEAPOLIS — The future is unclear for a proposed oil pipeline that would cross northern Minnesota.

Enbridge Energy on Tuesday announced it is investing in a different pipeline that would transport North Dakota crude oil — but not across Minnesota.

The Canadian company has proposed the $2.6 billion Sandpiper pipeline that would run from the Bakken oil fields through Minnesota to a terminal in Superior, Wisconsin.

Enbridge, based in Calgary, Alberta, and Houston-based Marathon Petroleum, a key partner in Sandpiper, are forming a joint venture to buy a stake in the Bakken Pipeline project, which would transport oil from North Dakota across the Midwest to Texas.

Once the new Bakken pipeline deal is complete, the company will “evaluate the scope and timing” of Sandpiper, Enbridge said in a statement.

In February, Enbridge said it expected to push back the startup date for Sandpiper to 2019. The pipeline proposal is going through the Minnesota regulatory process.

Environmentalists contend Sandpiper would threaten ecologically sensitive areas.

With Enbridge’s new pipeline investment, Sandpiper “will be put on the shelf,” Scott Strand, head of the Minnesota Center for Environmental Advocacy, told the Star Tribune. Strand’s group had pushed for a full environmental review of Sandpiper.

Late last year the Minnesota Public Utilities Commission ordered a full environmental impact review of Sandpiper. Enbridge has said the state’s regulatory process is delaying Sandpiper and another project, a replacement pipeline to carry Canadian crude oil across northern Minnesota.

“My guess, and it’s just a guess at this point, is that Sandpiper is not built in the near term while they take a stake in this (Bakken) pipeline,” Steven Paget, an analyst with First Energy Capital in Calgary, told Minnesota Public Radio News.

Environmental groups and American Indian tribes have opposed both Enbridge pipelines in Minnesota, saying if they break they would pollute wild-rice lakes and the Mississippi River headwaters.