Why it been so much harder to get gun-control bills through the U.S. Senate than the Colorado legislature? The New York Times explains the math. Colorado's most contentious new law, which banned magazines that hold more than 15 rounds of ammunition, passed its State Senate with 51 percent of the vote, and no Republican support. Under U.S. Senate rules, Democrats effectively need 60 percent of the vote to overcome the threat of filibusters and pass legislation there. That contrast helps explain why the nation's post-Newtown gun debate has not always followed the script that some predicted in the immediate aftermath of the shooting. New gun restrictions in Colorado, New York, Connecticut, and Maryland went further than many advocates on both sides had initially expected. At the national level, though, the president has faced an even steeper climb than many expected as he has labored to persuade the Senate to act on expanded background checks. Also, things move faster in some states. “We meet 120 days out of the year,” said Colorado Rep. Dominick Moreno. “You can't fiddle around like Congress does.”