Public Policy Polling’s latest Iowa poll paints a pretty picture for President Barack Obama going into the general election campaign.

Public Policy Polling surveyed 1,181 registered Iowa voters between May 3 and May 6, producing a margin of error of plus or minus 2.85 percent. Tom Jensen summarized the toplines here. The full polling memo is here (pdf). Barack Obama leads Republican nominee Mitt Romney by 51 percent to 41 percent. PPP’s previous Iowa poll in October 2011 showed Obama ahead of Romney by 46 percent to 42 percent (pdf).

From the polling memo released today:

Since last October, Obama has reversed his net-negative approval rating with Iowa voters. In October just 43% of voters approved of his job performance with 52% disapproving. Now he sits at 49% approval and 46% disapproval, including a 52-41 rating with independents.

By contrast, barely 1/3 of Iowans have a favorable opinion of Mitt Romney, weeks after he’s effectively wrapped up the Republican nomination. His approval rating stands at 34% favorable and 56% unfavorable, even worse than last October when he was at 34-52. Romney’s favorability rating among independent voters is an awful 28-59, and he still earns the disapproval of 25% of Republicans with just 63% approving. Meanwhile Obama enjoys the approval of 86% of Democrats and the disapproval of just 10%.

Jensen also notes,

The Ohio poll we released earlier today showed big problems for Romney with women and young voters and we see the same trend in Iowa. Obama’s up 20 points with women at 57-37 and has a 58-30 advantage with voters under 30. Obama’s running basically even with Romney among seniors, a group the Republican would need to win big in order to be successful in Iowa.

In February, Selzer and Co polled Iowans for the Des Moines Register and found Romney ahead of Obama by 46 percent to 44 percent. The full results from that survey are here (pdf).

It’s not clear whether Obama’s standing has improved in Iowa over the past few months, or whether PPP’s sample is markedly different from Selzer’s. PPP found Governor Terry Branstad at 43 percent approval and 43 percent disapproval. Selzer found Branstad in much more favorable territory: 56 percent of respondents approved of his work, while just 36 percent disapproved. I can’t think of any reason why Iowans’ opinion of Branstad would have changed that drastically during the past three months.

PPP’s sample contained 37 percent Republicans, 36 percent Democrats, and 27 percent independents. Registered no-party voters have a plurality in Iowa, and are more likely to vote in presidential elections than in midterms. Iowa has slightly more registered Republicans than Democrats.

I would caution Iowa Democrats not to celebrate too early. A survey of registered voters may not reflect the political preferences of Iowans who bother to cast ballots this fall. In addition, we’ve seen plenty of evidence that Obama’s team was concerned about holding this state. The president, Vice President Joe Biden, and First Lady Michelle Obama have each visited Iowa twice in recent months, and the Obama campaign has included Iowa in three separate television ad buys since early April. There’s still time for Obama to lose ground between now and November.

On the other hand, I question whether Romney’s campaign will invest the resources he would need to win here. Some recent polls have shown him trailing the president in several states that are more “must-win” for Republicans than Iowa (such as Virginia and Ohio). At the Iowa GOP’s Lincoln dinner in Des Moines last weekend, some speakers barely acknowledged that Romney exists. I doubt the state party is in a position to put together a strong GOTV effort for the Republican nominee. They will likely focus more on the Congressional and state legislative races.

If other surveys confirm PPP’s findings rather than Selzer’s, then by Labor Day Iowa may no longer make the list of presidential swing states.