Carter also had a 30% approval rating by the end of July ‘80. The campaign poll numbers reflected unease about Reagan as he had been pilloried as a press agent for WW3. Romney has at least 3 problems to overcome. Obama’s approvals go no lower than 40. Romney has not satisfied voters that Obama’s attacks are bogus. Romney unlike Reagan has not produced any kind of idea of what America will look like under a Romney presidency. Also Carter was an outsider who had to fend off the Left challenge for the nomination provided by teddy. Obama has no such problem with today’s dems.I think it will be Obama by Bush ‘04 numbers.
The other guy in that 1980 race was liberal Republican John Anderson who got 6.6 percent of the vote.