WASHINGTON - For the first time ever, a former U.S. president has come out against the Keystone XL pipeline.
The ex-president in question is Jimmy Carter.
The 39th president joined a group of Nobel laureates to sign a letter urging the current commander-in-chief to reject the pipeline from Canada.
The letter tells Barack Obama that he stands on the brink of making a choice that will define his legacy on one of the greatest challenges humanity has ever faced â€“ climate change.
It says his decision will either signal a "dangerous commitment" to the status quo, or "bold leadership" that will inspire millions counting on him to do the right thing for the climate.
Obama has signalled that a decision on the Alberta-to-Texas pipeline is imminent before summer.
He's being squeezed on the issue by different factions in his own party, which includes wealthy anti-Keystone donors but also pro-Keystone lawmakers at risk of losing their seats in more conservative areas in this fall's midterm elections.