PRINCETON, NJ -- Americans have more favorable than unfavorable opinions of both New Jersey Gov. Chris Christie and Ann Romney -- two featured speakers at the Republican National Convention in Tampa Tuesday night. At least a third of Americans, however, don't know enough about either to have an opinion.

Christie has become better known since Gallup last measured him in March 2011, when slightly over half of Americans did not have an opinion. However, the balance of opinion hasn't changed, because opinions then were slightly more positive than negative (27% vs. 22%), as they are now.

As would be expected, Republicans are strongly favorable toward Christie -- who was recently in the spotlight as one of Mitt Romney's possible vice-presidential picks -- and he is also better known among this group than he is to either independents or Democrats. Democrats are more negative than positive about the New Jersey governor -- but almost half don't know enough about him to have an opinion. Independents, a key group Christie's speech would be expected to reach at the GOP convention, tilt slightly positive in their appraisal of Christie, with four in 10 unable to rate him.

This is the first time Gallup has assessed Ann Romney, identified in the question as "wife of Mitt Romney." Republicans are highly positive about the potential first lady, while Democrats tilt negative. This negative reaction toward Mrs. Romney among those who identify with the opposite party is not unusual; recent polling shows that current first lady Michelle Obama is viewed more negatively than positively among Republicans nationwide.

Ann Romney's image splits 37% favorable, 25% unfavorable among independents -- again, a likely key target for her speech on Tuesday night.

It is widely assumed that Ann Romney's featured role at the convention is an effort to soften the image of her husband. Americans are more divided in their opinions of Mitt Romney than of his wife, with the gap in favorable (48%) and unfavorable (46%) opinions of him at two percentage points, contrasted with his wife's 18-point favorable tilt. Mitt Romney also has a substantial deficit when Americans are asked whether he or Barack Obama is more likable, with Obama "winning" on this dimension by 23 points. Whether Ann Romney can transfer some of her more positive positioning to her husband with her Tuesday speech remains to be seen.

Bottom Line

The choice of speakers to occupy precious prime-time slots at the political conventions is crucial in today's political environment -- given that television networks have limited their coverage of the conventions to these major speeches at night, and given that media messaging is now the biggest function of the conventions.

New Jersey's Christie has become one of the Republican Party's rising stars in recent years, and his tough, no-nonsense stances and blunt style of talking have generated discussions of the possibility of his running for president himself. He has become somewhat better known to Americans over the last year and a half, and his image remains more positive than negative, both overall and among independents. He thus will be giving his speech to at least a somewhat receptive audience.

Ann Romney is even better liked than Christie, although positive opinions of first ladies or prospective first ladies are generally the norm. Her assignment at the convention will be to create a more likable image for her husband, and future research will show how successful she is in doing so.

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