The percentage of those who said they were undecided has doubled over that time, from 10 percent in mid-September, to 20 percent now.
Tuesday's debate will be focused on economic issues, and the Washington Post-Bloomberg News poll shows that Romney and Cain have been the most effective at appealing to Republicans on those matters. Asked which Republican candidate would do the most to improve the economy, 22 percent of Republicans choose Romney, while 20 percent prefer Cain. Twelve percent of Republicans think Perry would do the most to improve the economy.
The Washington Post-Bloomberg News poll was conducted Oct. 6-9 by Princeton Survey Research Associates, surveying 391 Republican and Republican-leaning independent adults. The margin of error is +/- five percent.
The Gallup poll was conducted Oct. 3-7, surveying 1,064 Republican and Republican-leaning independent adults, for a margin of error of +/- three percent.
For the Gallup poll, the second choices of respondents who originally selected New Jersey Gov. Chris Christie, former Alaska Gov. Sarah Palin and former New York Mayor Rudy Giuliani were substituted; those individuals were included for only part of the survey.