Romney pollster Neil Newhouse said in a statement that the findings reflect the fact that Ryan, a House member since 1999, isn’t widely known.

USA TODAY/Gallup Polls of registered voters after the announcements of running mates since Dick Cheney in 2000 all showed more positive reactions. Only Dan Quayle in a 1988 Harris Poll of likely voters was viewed less positively than Ryan, with 52% rating Quayle as a “fair” or “poor” vice presidential choice. The Ryan poll includes all adults, not just registered voters…

The poll also finds 17% of adults say they’re more likely to vote for Romney in November because Ryan is his running mate — about the same impact Palin had for John McCain four years ago among registered voters.

Republicans, however, see the appeal in Ryan, who was hailed this weekend as a bold, innovative thinker by party stalwarts. The poll finds 36% of Republicans are now more likely to vote for Romney.