WASHINGTON // The New York mayor, Michael Bloomberg, is endorsing the US president, Barack Obama, for re-election, citing his leadership on climate change.
Mr Bloomberg says in an online opinion piece that Superstorm Sandy made the stakes of Tuesday's presidential election even clearer.
He says the climate is changing and that Mr Obama has taken major steps in the right direction.
An independent and former Republican, Mr Bloomberg says Republican presidential candidate Mitt Romney has reversed course on a number of positions.
Yesterday, Mr Romney was promising to get tough on China to help workers in the United States.
He is pledging, on his first day in office, to designate China a currency manipulator, a step that could lead to tariffs punishing China for policies that Americans believe unfairly keep Chinese products cheap, hurting US manufacturers.
Tariffs could trigger a trade war with a country that is the fastest-growing market for US exports. Even if they do not, the designation would bruise relations with Asia's emerging superpower.
The US seeks Chinese cooperation in international hot spots, such as North Korea and Iran, and wants to narrow differences over how to handle maritime territorial disputes in East Asia.
Given the potential repercussions, some foreign policy experts doubt Mr Romney would carry out the currency threat.
Both Mr Romney and Mr Obama have TV spots with China as a foil. Mr Romney accuses Mr Obama of being soft on China's trade practices; Mr Obama accuses Mr Romney of outsourcing US jobs to China when he ran a private equity firm.
The tone of the debate, labelling China a "cheat," has drawn withering criticism from the architect of US re-engagement with Beijing, the former secretary of state, Henry Kissinger, who has nonetheless endorsed Romney.
Mr Kissinger said that avoiding conflict between the powers is the most fundamental challenge for US foreign policy.
China's news agency Xinhua has accused Mr Romney of hypocrisy, saying much of his wealth was made with Chinese companies.