Yet another Iowa poll shows a close race between Hillary Clinton and Donald Trump. Quinnipiac surveyed 846 “likely voters” between August 9 and 16, producing a statistical margin of error of plus or minus 3.4 percentage points. Clinton led Trump by 47 percent to 44 percent in a two-way race, and by 41 percent to 39 percent in a field also including Libertarian Gary Johnson (12 percent) and Jill Stein of the Green Party (3 percent).

The Quinnipiac polling memo notes the large gender gap:

[Iowa] women back Clinton 56 – 38 percent, while men back Trump 51 – 37 percent. Trump leads 85 – 8 percent among Republicans. Independent voters are divided, with 45 percent for Trump and 41 percent for Clinton. Democrats back Clinton 97 – 1 percent.

Iowa voters give Clinton and Trump negative favorability ratings, 37 – 58 percent for her and 33 – 60 percent for him.

With both major-party nominees so well-known and so unpopular, and relatively few voters undecided with two and a half months to go, the key to winning Iowa will be executing an effective turnout operation, rather than a persuasion strategy.

Democrats have been dominating the “air war” this summer; Trump has yet to run any general-election television commercials, while Clinton’s campaign and allies including the super-PAC VoteVets have been running lots of tv ads during the summer Olympics. (I enclose below videos of two spots now in rotation.) Democratic vice presidential nominee Tim Kaine received lots of media coverage in Iowa’s largest markets today, headlining a morning rally in Cedar Rapids before making an unscheduled Iowa State Fair visit in the afternoon. Trump will return to Iowa for Senator Joni Ernst’s “Roast and Ride” fundraiser on August 27, which is sure to receive heavy media attention statewide.

The “ground war” will be especially important once early voting begins on September 29. More than 43 percent of the Iowans who cast ballots in the 2012 presidential election voted early, and women are more likely than men to vote before election day. Iowa Democrats registered more new voters in the final weeks of the 2012 campaign and did a better job identifying and turning out no-party voters who supported President Barack Obama.

Margins of error for subsamples are always higher than for an opinion poll as a whole, but let’s assume Trump is really ahead among Iowa no-party voters, as Quinnipiac’s poll indicates. Effective GOTV by the Democratic coordinated campaign could compensate for that problem by banking more votes from Democrats and independents already identified as Clinton supporters. (Democrats have two dozen Iowa field offices open already.) The Quinnipiac sample consisted of 28 percent self-identified Democrats, 28 percent Republicans, and 39 percent independents.

Any comments about the presidential race are welcome in this thread. Cross-tabs for the Quinnipiac poll are available here.

The super-PACs VoteVets and Priorities USA are running this 60-second spot, “Michelle,” in some Iowa markets. Michelle DeFord, a Gold Star mother, talks about her son who died in Iraq and her “sense of outrage” upon hearing Trump question Ghazala Khan, who stood alongside her husband at the Democratic National Convention.

Of the Clinton ads I’ve seen lately, the most effective is “Someplace,” featuring former CBS late night host David Letterman grilling Trump about where items in his clothing line were manufactured.