PRINCETON, N.J. -- Hillary Clinton is one of a few potential 2016 presidential candidates to have a significantly higher favorable (50%) than unfavorable (39%) rating among the American public. And the 89% of Americans who are familiar enough with Clinton to have an opinion of her is more than any other potential 2016 presidential candidate. Clinton's relatively high scores on both dimensions give her a better starting position regarding her image than other competitors would have in the 2016 U.S. presidential election.

These results are based on a March 2-4 Gallup poll of 1,522 U.S. adults, conducted just as revelations about the private email account Clinton used to conduct business while secretary of state became a major news story, but before her Tuesday press conference addressing questions about the issue.

The graph plots 16 potential candidates --11 Republicans and five Democrats -- on a two-dimensional chart displaying their familiarity and favorability ratings. The candidates who appear in the upper-right quadrant are in the most advantageous position at this point as they are both relatively well-known and have higher favorable than unfavorable ratings. In addition to Clinton, Republicans Jeb Bush, Mike Huckabee and Rand Paul reside in this space. However, Americans rate each of those Republicans only slightly more positively than negatively, with net favorable scores of +2 or +3, compared with Clinton's +11. And Huckabee and Paul have just slightly above average familiarity. Generally speaking, the further candidates are away from the intersecting lines, the better their image.

Candidates in the lower-right quadrant -- including Chris Christie and Rick Perry -- are among the better-known candidates, but Americans do not view them positively overall. Joe Biden and Ted Cruz are on the edges of this quadrant. Biden is well-known, but opinions of him are equally positive and negative, while Cruz is viewed negatively but has average familiarity. The challenge for these politicians should they run for president is to alter existing perceptions about them so they are more positive than now, or alternatively, to get the smaller group of Americans who are unfamiliar with them to get to know them and view them positively.

Americans view candidates in the upper left quadrant -- including Republicans Marco Rubio, Scott Walker, Bobby Jindal, and Ben Carson and Democrat Elizabeth Warren -- more positively than negatively, but these candidates have lower than average familiarity. If these candidates can maintain their positive image as they become better known -- not an easy task -- they would rank among the stronger presidential contenders. Right now, Rubio is closest to crossing that threshold, given that the 47% of Americans familiar with him is only slightly below the 50% average of the 16 candidates, while he has a +5 net favorable score. Carson has a +12 net favorable rating, essentially the same as Clinton's, but is among the least well-known candidates, with 28% of Americans having an opinion of him.

Republican Rick Santorum, Democrat Jim Webb and Bernie Sanders -- an independent who may seek the Democratic nomination -- have the biggest challenges related to their image because they are largely unknown and not viewed positively by those who do know them.

The full favorability and familiarity ratings among all Americans for each of the 16 candidates tested in the survey appear in the table.

In forthcoming analyses, Gallup will report the ratings of the potential Democratic presidential candidates among Democrats and the potential Republican presidential candidates among Republicans, giving a sense of how each rates image-wise in the beginning stages of the race for each party's nomination.

Clinton in Slightly Weaker Position Than Last Summer

Gallup conducted a similar analysis of the images of potential 2016 presidential candidates last July. Even as several of these individuals have attracted regular media attention in anticipation of a possible presidential bid, none of these would-be candidates has made significant gains in familiarity. But Perry, Cruz and Christie have moved from net positive favorable ratings to net negative, while Bush has moved in the other direction.

Then, as now, Clinton was the best-known potential candidate among those rated, but her favorability rating is lower today. Last July, 55% of Americans had a favorable opinion of her and 36% an unfavorable one, for a net favorability score of +19, compared with the current +11 score.

More generally, her favorability ratings have declined in recent years as she has moved from a less overtly partisan role as secretary of state -- during which time her favorable routinely topped 60% -- to a more clearly partisan role as an expected presidential candidate. Still, even with diminished favorability currently, Americans do not view any of the other well-known candidates as positively as they do Clinton.

Gallup has a long trend line on Clinton's favorable ratings, from her various roles as first lady, U.S. senator, 2008 presidential candidate and secretary of state. At a similar point in early March 2007, before her last presidential campaign, she was better known than now (96% were familiar with her) and had a similar favorability profile (+12, 54% favorable and 42% unfavorable). But her favorable ratings varied over the course of that campaign, including times in which more Americans had a negative than a positive opinion of her. She eventually lost the 2008 Democratic nomination to Barack Obama after starting the campaign as the clear front-runner.

Implications

At this point, slightly less than a year before the first primaries and caucuses, Hillary Clinton is the best-known potential presidential candidate and among the most positively rated. The other possible candidates are all less well-known than Clinton at this point, but as Americans get to know them better in the months ahead, these candidates' challenge will be to either maintain or create more positive images.

Right now, Bush and Christie come closest to Clinton in familiarity among the GOP field, and Carson and Rubio come closest to her on favorability. All of these candidates are, however, currently weaker than Clinton on the other of those two dimensions.

The candidates' images will change over the course of the presidential campaign as a result of increased attention from voters, increased media scrutiny, their performance in scheduled debates and how they perform in the early primaries and caucuses.

Because Americans view presidential candidates in largely political terms, many candidates might not end up with favorable ratings much higher than 50%. Regardless of how high a candidate's favorable rating gets, one minimum requirement for being a viable candidate is having a higher favorable than unfavorable rating among the American public.

Survey Methods

Results for this Gallup poll are based on telephone interviews conducted March 2-4, 2015, on the Gallup U.S. Daily survey, with a random sample of 1,522 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia. For results based on the total sample of national adults, the margin of sampling error is ±3 percentage points at the 95% confidence level. All reported margins of sampling error include computed design effects for weighting.

Each sample of national adults includes a minimum quota of 50% cellphone respondents and 50% landline respondents, with additional minimum quotas by time zone within region. Landline and cellular telephone numbers are selected using random-digit-dial methods.

View survey methodology, complete question responses, and trends.

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