Could shooting be a tipping point in gun-control debate?

The question surfaces each time a mass murder unfolds: Will this one change the political calculus in Washington, capital of the United States, against tougher gun control?

The answer, after the Virginia Tech killings, the attempted assassination of Congresswoman Gabby Giffords, the Colorado movie-theater attack, the Wisconsin Sikh temple shootings, and more: No.

But now? The massacre in Newtown, Connecticut - which took the lives of 20 children and six adults at the school, the gunman's mother at home, and the gunman himself - stands as a possible tipping point in Washington's decade-long aversion to even talking about stricter gun laws.