Conservative group Americans for Prosperity (AFP) is asking 2.3 million people to contact the White House and urge the president to sign legislation authorizing the Keystone XL pipeline.
The group, which is backed by billionaire donors Charles and David Koch, is asking 2.3 million people tied to the organization to call the White House switchboard to support the oil sands project.
“The Keystone pipeline has been approved by the House, the Senate, and has passed environmental review," said AFP President Tim Phillips.
"Vetoing this legislation would mean putting special interests and ideology above American workers. We ask President Obama to do the right thing and approve the Keystone plan."
The AFP plans to direct hundreds of daily calls to the White House ahead of the expected veto.
Republican leaders held a ceremony Friday to sign the bill approving Keystone, but will hold off on sending it over to the White House until after next week's Presidents Day recess.
Administration officials repeated this week that President Obama will veto the bill, arguing it circumvents the ongoing process at the State Department.