US consumer confidence unexpectedly weakened in December as the post-election euphoria fizzled and concerns about future business conditions emerged. The Conference Board said on Monday its consumer confidence index dropped to 104.7 this month from an upwardly revised 112.8 in November. Economists polled by Reuters had forecast the index climbing to 113.3 from the previously reported 111.7. “Consumer views of current labor market conditions continued to improve, consistent with recent jobs and unemployment data, but their assessment of business conditions weakened,” said Dana Peterson, the chief economist at the Conference Board.