The Iowa Poll gave Cain, a former pizza company executive from Georgia, 23 percent to 22 percent for Romney, a former Massachusetts governor. That's a 13-point improvement for Cain since the newspapers last poll in late June and a significant jump since he placed fifth in the mid-August Iowa straw poll.
Neither candidate has done much personal campaigning in the state, the newspaper said.
U.S. Rep. Ron Paul of Texas placed third with 12 percent, followed by Rep. Michele Bachmann of Minnesota -- who won the straw poll and had 22 percent support in June -- at 8 percent, Texas Gov. Rick Perry and former House Speaker Newt Gingrich tied at 7 percent, former Sen. Rick Santorum of Pennsylvania at 5 percent and former Utah Gov. Jon Huntsman at 1 percent.
The Register's Iowa Poll queried 400 likely GOP caucus-goers by telephone Oct. 23-26. The poll has a 4.9 percentage-point margin of error.