Barrack Obama. With stocks tumbling and bonds signaling a slide toward deflation, a cheaper dollar is just what the doctor ordered. The weakness may be short-lived, but if it becomes a trend, the US will breath a sigh of relief.
US equities would be a lot more comfortable as well if it had a currency tailwind at its back (from a multi-national earnings perspective) than a headwind in its face.
Pronounced USD weakness would hurt US Treasuries, but a gradual decline would be taken in stride.