Sen. Dianne Feinstein's bill banning assault weapons and high-capacity ammunition clips will struggle to pass the Senate with a simple majority if brought to the floor for a vote, Bloomberg reported today. At least six Senate Democrats are either wobbly on the ban or are flat-out opposed. No Republican Senator has spoken in support of the ban.

If the rest of the Democrat's 55-vote majority hold together to support the ban, that's still one vote short of passage. But a simple majority is rarely enough to pass anything in Washington these days. The near-certain use of the filibuster on Feinstein's assault weapons bill raises the threshold of passage to 60 votes.