Washington (CNN) -- The fate of the controversial Keystone pipeline wasn't the only thing at stake during a crucial vote in the Senate on Tuesday. The vote blocking legislation that would have authorized the pipeline's construction previews a new era of animosity between resurgent Republicans in Congress and President Barack Obama. It could also seal the fate of embattled Democratic Sen. Mary Landrieu of Louisiana, who had made pushing the measure a focal point in an uphill battle to fend off a GOP challenger in a runoff election next month. Landrieu fell one vote short of securing the support necessary to advance the legislation. All 45 Republicans voted for the measure and 14 Democrats did, too. But she needed one more Democrat to join her to reach the critical 60 vote threshold.
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The Senate blocked a bill that would have authorized construction of the Keystone pipeline
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The bill is being championed by Democratic Sen. Mary Landrieu ahead of her Dec. 6 run-off election
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Landrieu had 14 of the 15 Democrats she needs to reach the 60 votes necessary for passage
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The failure to muster enough @placeholder votes occurred even though Landrieu had insisted for days that she had the votes she needed.
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In her speech, Landrieu made an aggressive case in favor of approving the pipeline while other @placeholder dissented.
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If the Senate ultimately approves the measure, @placeholder could be poised to issue what would be just the third veto of his nearly six year presidency.
Barack Obama
Republicans are considering how to respond if @placeholder follows through with a pledge to revise immigration policies by the end of the year.