New York mayor Michael Bloomberg has backed President Barack Obama over Republican Mitt Romney, saying the incumbent Democrat will bring critically needed leadership to fight climate change after the devastation wrought by Superstorm Sandy.
The endorsement from the politically independent mayor of the biggest US city was a major boost for Mr Obama, who is spending the campaign's final days trying to win over independent voters whose voices will be critical in determining the winner of Tuesday's election.
Both candidates had eagerly sought the nod from Mr Bloomberg, who did not endorse a presidential candidate in 2008 and has publicly grumbled about both Mr Obama and Mr Romney.
But Mr Bloomberg said the possibility that Sandy resulted from climate change had made the stakes of the election that much clearer.
"We need leadership from the White House, and over the past four years President Barack Obama has taken major steps to reduce our carbon consumption," Mr Bloomberg wrote in an online opinion piece.
A full-throated stamp of approval this was not. Even as he pledged to cast his vote for Mr Obama's re-election, Mr Bloomberg faulted the president for discounting centrists, trading in divisive, partisan attacks and failing to make progress on issues such as gun control, immigration and the federal deficit.
The billionaire businessman and former Republican also praised Mr Romney as a good man who would bring valuable business experience to the White House, but said Mr Romney had reversed course on issues such as healthcare and abortion. "If the 1994 or 2003 version of Mitt Romney were running for president, I may well have voted for him," he said.
Mr Bloomberg's endorsement could have the effect of injecting climate change and the environment into the political conversation just five days before the end of a campaign in which both topics have been virtually absent.
"Our climate is changing," Mr Bloomberg said. "And while the increase in extreme weather we have experienced in New York City and around the world may or may not be the result of it, the risk that it might be - given this week's devastation - should compel all elected leaders to take immediate action."
To the dismay of environmental activists, climate change never came up during any of the three presidential debates and has been all but absent throughout the rest of the campaign. When Mr Romney invoked the environment in his August speech accepting the Republican nomination, it was to mock his rival for making the issue a priority.