原因完全是政治上的：党派两极分化达到了前所未有的程度，眼看就把美国经济逼下“财政悬崖 ” — —2013年开始自动增税减支，除非民主党和共和党达成其他一致方案。
The reason is entirely political: partisan polarization has reached levels never before seen, threatening to send the US economy tumbling over the “fiscal cliff” – the automatic tax increases and spending cuts that will take effect at the beginning of 2013 unless Democrats and Republicans agree otherwise.