Poll: Obama 44, Romney 32, Paul 18

Not surprisingly, much of the potential support for Paul comes from independent voters. Roughly a quarter of independents who say they would back Obama or Romney in a two-person race say they would switch to Paul if he runs, leaving the independent vote divided almost evenly between Obama (31%), Romney (33%) and Paul (26%). Put in other terms, Obama loses nine percent and Romney 17 percent of independent voters to Ron Paul if he decides to run.

Not only does Romney lose more independent voters to Ron Paul than does Obama, but a Paul third-party candidacy also threatens to steal away some of the conservative Republican vote as well. Fully 96% of conservative Republicans say they would back Mitt Romney in a two-person race against Obama. But that support falls to 77% in a three-person race, with 19% saying they would switch to backing Ron Paul. There is no comparable loss of support for Obama among either liberal or moderate and conservative Democrats.