OTTAWA, Ontario -- When Canadian Prime Minister Stephen Harper visits Mexico this week for a summit of North American leaders, one of his key objectives will be to push for U.S. approval of a controversial oil pipeline.

The Keystone XL project -- first proposed back in 2008 -- would bring crude from Canada's oil sands in Alberta across the U.S. Midwest to Texas via a pipeline stretching 1,179 miles (1,897 kilometers).

The project has pitted environmental groups against the oil industry, which has argued that it will bring much-needed jobs to the United States and help fulfill the U.S. goal of energy self-sufficiency.

It also has caused strains in relations between Ottawa and Washington. The United States has to approve some 875 miles of the new route.

Harper's meeting with U.S. President Barack Obama on Wednesday in the Mexican city of Toluca will be their first face-to-face talks since September, at a summit in Russia.

The Canadian prime minister -- who will be accompanied by his ministers of trade, natural resources and public safety -- has said the Keystone XL pipeline is crucial for his country's economic prosperity.

And he has expressed deep frustration that six years after it was first proposed, oil giant TransCanada's US$5.3 billion project remains in limbo.

"Of course, Harper will be tempted to pressure Obama," said Pierre-Oliver Pineau, a professor in energy sector management at HEC Montreal business school.

But he is unlikely to quickly sway the U.S. leader, who faces opposition from environmentalists within his Democratic party. The United States has also increased its own oil production, making supplies from Canada less vital.