Environmental opponents of the Keystone XL tar sands pipeline aimed to deluge the White House and Congress with phone calls on Friday, slamming a Republican plan to speed approval of the project in exchange for extending a payroll tax cut.

"Red alert - call the White House and tell them not to back down to big oil on Keystone," environmental activist Bill McKibben said in a tweet. McKibben mobilized some 10,000 demonstrators outside the White House earlier this year to protest the pipeline.