Keystone backers scramble for last vote on bill, Boehner warns Obama against veto

Democratic Sen. Mary Landrieu was racing to win over one last senator in the run-up to a critical vote on the Keystone pipeline set for Tuesday evening, with not only the energy project but her political future potentially at stake.

So far, 59 senators have publicly voiced support for the bill which would green-light the pipeline -- one short of the 60 needed to secure passage and send the legislation, for the first time, to President Obama's desk.

Obama, as well, is under pressure to sign the bill...