OTTAWA -- Republicans turned up the heat on U.S. President Barack Obama on Friday to reverse his decision to delay what was described at a congressional hearing as the safest oil pipeline ever proposed.

A parade of witnesses appeared at a House sub-committee meeting on energy to defend the safety and economic benefits of the Keystone XL pipeline, and to warn of the consequences should it rupture.

And in between partisan sniping between Democrats and Republicans, pipeline junkies learned Alberta-based TransCanada Corp. has adopted 57 additional safety measures, including 21,000 censors linked to satellites to detect problems.

"This is the most technologically advanced and safest pipeline ever proposed," Rep. Ed Whitfield said, noting XL has a censor every 167 meters to monitor pressure, flow rates and to identify leaks.

Republicans introduced legislation in the Senate this week that would force the State Department to issue a permit within 60 days to kick start the project critics say Obama delayed until after next fall's election to keep his environmental base onside and money flowing to his re-election bid.

Alex Pourbaix, TransCanada's president of energy and oil pipelines, reminded lawmakers no other pipeline has gone through as many reviews and as much scrutiny since the oil giant applied for a construction permit 40 months ago.

The $7 billion pipeline would transport 830,000 barrels of crude daily to the Gulf Coast, where specialized refineries process a similar product from Venezuela.

"This has been by far the most exhaustive and detailed review ever conducted of a crude oil pipeline in the U.S.," said Pourbaix.

Representatives from organized labour pitched their support and the need for the 20,000 shovel-ready jobs XL would produce and spinoff work.

Alternative energy producers and a representative from a Nebraska citizens group opposed to the pipeline asked the committee not to rush the project.