Poll Shows Obama and Romney Close in Iowa Barack Obama and Mitt Romney are essentially tied in Iowa, according to the latest poll conducted for the The Des Moines Register. Among likely voters surveyed, 49 percent support Mr. Obama and 45 percent back Mr. Romney. The poll has a margin of sampling error of plus or minus four percentage points. Only 2 percent of respondents were undecided, but 10 percent said they could still change their minds. However, voters have already begun to cast their ballots as early voting in Iowa started last Thursday. Mr. Obama won Iowa four years ago, but it swung Republican in the previous two presidential elections, backing George W. Bush in 2000 and 2004. Representative Paul D. Ryan of Wisconsin is considered an asset to Mr. Romney's campaign by 56 percent of voters surveyed, while 47 percent regard Vice President Joseph R. Biden Jr. a liability. But the favorability rating for the two running mates is fairly even: 46 percent have a favorable opinion of Mr. Ryan and 41 percent are unfavorable while 45 percent have a favorable view of Mr. Biden and 45 percent are negative. On the other hand, Mr. Obama's favorability rating is higher than Mr. Romney's. A majority of voters, 54 percent, have a positive impression of Mr. Obama and 43 percent have an unfavorable opinion. In contrast, 44 percent have a favorable opinion of Mr. Romney and more, 51 percent, hold a negative view. The telephone poll was conducted Sept. 23-26 with 650 likely voters by Selzer and Company.