Only one in four Americans know how many votes a Senate filibuster requires. One in three know the name of the chairman of the Republican Party. One in two know the Democratic leader of the US Senate.

Health care? Fewer than one in three Americans even know that no Republicans voted for the Senate health care overhaul.

Americans' ignorance about politics isn't new, but the latest results from the Pew Poll suggest few are really paying attention.

Half of Americans don't even know that Stephen Colbert is a comedian. And among those surveyed, only one in three Democrats knew that Sen. Harry Reid (D-NV) was the Democratic leader.

"About four-in-ten (39%) know that Nevada Democrat Harry Reid is the majority leader of the U.S. Senate," Pew reports. "About a third (32%) correctly pick Michael Steele as the chairman of the Republican National Committee. Interestingly, nearly half of Republicans (48%) are able to identify Reid as Senate majority leader compared with just a third (33%) of Democrats. More Republicans can identify Reid as majority leader than can identify Steel as chairman of the RNC (37%)."

"About four-in-ten (41%) correctly say that Stephen Colbert is a comedian and television talk show host," Pew adds.

Notably, those who are more clueless about politics hail from the under 30 age bracket -- except for the question about Colbert.

"This is the only question on the quiz that more people younger than 30 than older people answer correctly (49% vs. 39%)," Pew notes.

Adds Pew:

About six-in-ten (59%) correctly identify China as the foreign country holding the most U.S. government debt. Nearly as many (57%) know that the United States imports two-thirds of the oil it consumes. As was the case in previous knowledge surveys, a majority (55%) knows the current unemployment rate is about 10%. However, far fewer (36%) correctly estimate the current level of the Dow Jones Industrial Average at about 10,000 points.

The news quiz, conducted by the Pew Research Center for the People & the Press Jan. 14-17 among 1,003 adults reached on cell phones and landlines, asked 12 multiple choice questions on subjects ranging from economics and foreign affairs to prominent people in the news. Americans answered an average of 5.3 questions correctly.

The survey finds that while the public struggled with most of the political questions on the survey, most Americans (56%) know that there currently is more than one woman serving on the Supreme Court. Notably, this is the only question on the quiz where as many women as men answer correctly; men scored significantly better on other questions.

In response to questions about terrorism and national security, half (50%) correctly identify Yemen as the country where intelligence officials believe the suspect in an attempted Christmas Day airline bombing received training and bomb materials. A slightly smaller percentage (43%) knows that during all of 2009 there were more American military fatalities in Afghanistan than in Iraq; 32% said more U.S. troops were killed in Iraq.

The poll was conducted Jan. 19, prior to the election of Massachusetts Senator-to-be Scott Brown.