The public has consistently expressed strong interest in the health care debate, but relatively few Americans can correctly answer two key questions related to the Senate’s consideration of health care legislation.

In the latest installment of the Pew Research Center’s News IQ Quiz, just 32% know that the Senate passed its version of the legislation without a single Republican vote. And, in what proved to be the most difficult question on the quiz, only about a quarter (26%) knows that it takes 60 votes to break a filibuster in the Senate and force a vote on a bill. The survey was conducted before Massachusetts Republican Scott Brown won a special election to the Senate on Jan. 19; Brown’s election means Senate Democrats can no longer count on a 60-vote majority once he takes office.