variables. Some political scientists speculate there is a coattail effect (when a popular president or party position has the effect of reelecting incumbents who win by "riding on the president's coattails"), although there is some evidence that the coattail effect is irregular and possibly declining since the 1950s. Some districts are so heavily Democratic or Republican that they are called a safe seat; any candidate winning the primary will almost always be elected, and these candidates do not need to spend money on advertising. But some races can be competitive when there is no incumbent. If a seat becomes vacant in an open district, then both parties may spend heavily on advertising in these races; in California in 1992, only four of twenty races for House seats were considered highly competitive. Television and negative advertising Since members of Congress must advertise heavily on television, this usually involves negative advertising, which smears an opponent's character without focusing on the issues. Negative advertising is seen as effective because "the messages tend to stick." These advertisements sour the public on the political process in general as most members of Congress seek to avoid blame. One wrong decision or one damaging television image can mean defeat at the next election, which leads to a culture of risk avoidance, a need to make policy decisions behind closed doors, and concentrating publicity efforts in the members' home districts. Perceptions Prominent Founding Fathers writing in The Federalist Papers felt that elections were essential to liberty, that a bond between the people and the representatives was particularly essential, and that "frequent elections are unquestionably the only policy by which this dependence and sympathy can be effectually secured." In 2009, few Americans were familiar with leaders of Congress. The percentage of Americans eligible to vote who did, in fact, vote was 63% in 1960, but has been falling since, although there was a slight upward trend in the 2008 election. Public opinion polls asking people if they approve of the job Congress is doing have, in the last few decades, hovered around 25% with some variation. Scholar Julian Zeliger suggested that the "size, messiness, virtues, and vices that make Congress so interesting also create enormous barriers to our understanding the institution... Unlike the presidency, Congress is difficult to conceptualize." Other scholars suggest that despite the criticism, "Congress is a remarkably resilient institution... its place in the political process is