The large leak was discovered Thursday in South Dakota, prompting crews to shut down the pipeline.
TransCanada calls Obama's rejection of the proposed crude oil pipeline "arbitrary and unjustified." The company is now seeking $15 billion for costs and damages.
TransCanada on Monday announced it was asking the State Department to suspend its review of the pipeline application while regulators in Nebraska consider a potential route through the state.
During speeches in Vancouver and Calgary, Clinton defers to her successor on questions about the crude oil project. "What pipeline?"