Nebraska Gov. Dave Heineman has signed two bills into law to regulate oil pipelines within the state's borders.
One measure would subject the proposed Keystone XL pipeline to a state environmental review.
The other would direct the Public Service Commission to review future projects with public input.
Jane Kleeb, whose Bold Nebraska group is leading a campaign opposing the pipeline, will outline later Tuesday how the pipeline's critics plan to proceed once the special session ends.
The 2,700-kilometre Alberta-to-Texas line has pitted environmental groups and local landowners along the pipeline's route against energy producers and various interests that want to wean the United States off oil from the Middle East and countries such as Venezuela.