House rules allow members to raise questions of the privileges of the House, which can be used to stop proceedings affecting the safety, dignity and integrity of the House. Questions must be put in the form of a resolution.
Questions that are raised by party leaders or have been reported from a committee must be considered right away.
Others, like Grayson's, must be handled within two days. But the House Speaker can determine whether the question qualifies. If the Speaker accepts it, that starts a debate on the question.
In this case, Grayson appears to be arguing that the legislation is unconstitutional, since it would effectively have Congress deem the northern leg of the pipeline as approved.
Republican supporters of the bill have argued that Congress has the authority under the Constitution to regulate international commerce. They say the Keystone pipeline falls into that category because it would move tar sands oil between Canada and the United States.
Opponents can point to recent court decisions saying that the responsibility for permitting for transnational pipelines has fallen on the president for several years. But if Grayson's question comes up for a debate, Republicans are likely to argue that they are seeking to re-establish congressional authority over pipeline decisions — especially the Keystone pipeline, which the GOP says has been unduly delayed by Obama for several years.