Public Policy Polling’s latest Iowa survey finds President Barack Obama leading Republican Mitt Romney by 48 percent to 43 percent.

Two months ago, PPP found Obama up by 10 in Iowa, but that poll looks like an outlier. The Obama campaign has been blanketing the state with multiple negative ads on Romney, not the typical behavior of a candidate who’s comfortably ahead. In addition, recent surveys from NBC/Marist and Rasmussen have found the presidential candidates in a virtual tie here.

For the latest poll, PPP surveyed 1,131 Iowa voters between July 12 and July 15, producing a statistical margin of error of +/-2.91 percent. Full results and crosstabs are here (pdf). The sample contained 35 percent registered Democrats, 34 percent registered Republicans, and 30 percent no-party voters. It’s too early to guess whether this proportion will accurately reflect the universe of Iowans who cast a ballot this fall. The statewide statistical report from 2008 indicates that more Democrats voted than Republicans or independents, but at that time Iowa Democrats had a significant voter registration advantage, which is gone now.

In any event, PPP found Obama leading thanks to his strength among women and, to a lesser extent, independents. Tom Jensen notes,

Iowa voters have flipped from narrow approval of Obama (49/46) to narrow disapproval of him (47/49) over the last couple months. His numbers are pretty steady with Democrats and Republicans but with independents he’s gone from 52/41 to 45/48. Fortunately for Obama, Romney’s not very popular either. Only 37% of voters have a favorable opinion of him to 55% with a negative one. That – 18 spread is up a bit from its – 22 standing at 34/56 the last time PPP polled Iowa, but it’s still indicative of an electorate that’s not exactly warming up to him yet.

Iowa really exemplifies how critical women are to Obama’s reelection hopes. He leads 54-37 with them, helping to offset a 48-43 disadvantage with men. Iowa’s also a state where Obama continues to benefit from a party unity gap, taking 87% of Democrats to Romney’s 84% of Republicans. If Romney can close that up the state will tighten further. Obama leads 46-38 with independents, although that’s down a good deal from his 54-34 lead in May.

The good news for Obama is that of the 1,528,715 Iowans who cast ballots in the 2008 general election, 823,712 were women.

Governor Terry Branstad’s approval rating is 45 percent in PPP’s poll, with 43 percent of respondents saying they disapprove of his job performance and 12 percent not sure. Representative Steve King is not well-liked statewide, but PPP’s numbers don’t tell us how popular he is in the new fourth Congressional district.

Respondents disagree with Obama’s new immigration policy (which wasn’t described in the question wording) by a 47 percent to 35 percent margin. They disagreed with the Supreme Court’s ruling on health care reform by 46 percent to 41 percent.

I am disappointed that PPP chose to ask respondents to guess the presidential candidates’ ages, instead of something more relevant, like a question about acceptance of same-sex marriage rights/support for a constitutional amendment banning same-sex marriage.

Any comments about the presidential election are welcome in this thread.