A mix-up over amendment language has robbed House Republicans of their latest opportunity to vote for greenlighting the Keystone XL oil pipeline.

Reps. Lee Terry (R-Neb.) and Connie Mack (R-Fla.) withdrew their amendment to a GOP energy bill that would have approved the pipeline after realizing that key language was missing, a Terry aide told POLITICO.

"Some language was omitted from the amendment and after rereading it, we realized the error and it completely changed the intent of the amendment," the aide said.

In the rush to get the amendment approved, four lines were left out that "added another layer of approval that we did not intend," the aide said, blaming the mistake on "human error."

Terry, a vocal proponent of the pipeline, hopes to talk with House Speaker John Boehner about adding the correct version of the amendment to another piece of legislation, according to the aide.