While Republicans said increased oil supplies to U.S. refineries should help lower U.S. gasoline prices, Democrats argued that the pipeline would give Canada access to global oil markets through the Gulf.

"This oil is not for domestic consumption," said Rep. Gerry ConnollyGerry ConnollyDem rep: Trump threatened Mueller by trying to set limits for Russia probe Overnight Cybersecurity: State Department reportedly eliminating cyber office | Senate Intel chief avoids White House during Russia probe | Dem pushes 'ethical hacking' resolution House panel approves backup plan to improve agencies' IT MORE (D-Va.). "This oil is for foreign export. It has very little to do with domestic oil supply, or it might have very little to do with domestic oil supply."

Connolly said proof of this is that House Republicans rejected his amendment and another similar one that would have ensured that most refined petroleum products derived from oil received through the pipeline were sold in the U.S. market. The House did not make these amendments in order.

"The fact that the Rules Committee would not put that amendment on this floor ... I think gives the lie to the intent behind the extension of this pipeline," Connolly said.

Rep. Alcee Hastings (D-Fla.) added that TransCanada itself expects the price of oil to increase in the U.S. as a result of the pipeline.

"TransCanada's application actually indicates that it expects the price of crude oil to increase by $6.55 per barrel in the Midwest, and $3 elsewhere after the expansion is completed," he said.

The House approved the rule for debating the bill by a 246-171 vote just after 1:30 p.m. and was expected to move to general debate on the bill later this afternoon. Eleven Democrats supported the rule.

-- This story was updated at 1:38 p.m. to reflect the vote on the rule.