They were against the fence before they were for it

As reported by the Washington Times (HT: Powerline):

The Senate last night gave final approval for construction of 700 miles of fencing along the U.S.-Mexico border...

... Eight Democratic senators who supported the bill last night switched their position from the previous day, when they voted to block the fence. They are Sens. Barbara Boxer of California, Thomas Carper of Delaware, Hillary Rodham Clinton of New York, Christopher J. Dodd of Connecticut, Tom Harkin of Iowa, Herb Kohl of Wisconsin, Barack Obama of Illinois and Charles E. Schumer of New York.

Many of the Democrats who joined Republicans on the vote either face close elections this November or represent mostly conservative states...