Moderate Republican Doug Gross has released another 2010 gubernatorial campaign poll through his group, the Iowa First Foundation.

Gross, who served as a top aide to former Republican Gov. Terry Branstad and was his party’s 2002 gubernatorial nominee, has been releasing the results of his latest round of surveys, conducted July 23-26, this week. Today, he released favorability numbers (pdf) for Gov. Chet Culver, former governors Tom Vilsack and Branstad, and a slew of Republicans who could be on the gubernatorial primary ballot next year.

While Branstad’s numbers look good, the rest of the GOP gubernatorial field continues to languish in relative obscurity. Culver, the incumbent, still appears to be in a decent position ahead of next year’s election.

The results, compiled by Republican pollsters at Hill Research Consultants, peg Culver’s favorability rating among likely Iowa voters at 52 percent. 38 percent view the current governor unfavorably, with a margin of error of 3.7 percentage points.

Branstad, who was governor for four terms during the 1980s and 1990s and is rumored to be considering a return to politics, is viewed favorably by 68 percent and unfavorably by 15 percent of likely voters.

In between Culver and Branstad are Vilsack, who is viewed favorably by 55 percent and unfavorably by 25 percent, and President Barack Obama, who is viewed favorably by 56 percent and unfavorably by 38 percent.

Culver, Branstad, Vilsack, and Obama all enjoy high name recognition. Vilsack is known by 89 percent of likely voters, Branstad is known by 90 percent, Culver is known by 96 percent, and Obama is known by 99 percent.

None of the other names that the poll asked about — state Rep. Chris Rants (R-Sioux City), social conservative activist Bob Vander Plaats (R-Sioux City), state Sen. Paul McKinley (R-Chariton), Poweshiek County Attorney Mike Mahaffey (R-Montezuma), state Rep. Rod Roberts (R-Carroll), and business executive Christian Fong (R-Cedar Rapids) — has the same level of name recognition. Vander Plaats comes closest with 60 percent, followed by Rants and Mahaffey, who are hovering near 40 percent. None of the other candidates crack 30 percent. For that reason, the favorability numbers for those candidates probably don’t mean a lot, since voters still have a lot to learn about all of them.

Moreover, based on the way the question was phrased, I suspect all of the name recognition numbers are slightly inflated, because poll respondents had to volunteer the fact that they didn’t recognize a name while answering the favorable/unfavorable question in order for a “no” to register.

What is interesting, I think, is that Culver and Obama both achieve similar numbers in the poll. Obama seems to elicit more passionate responses from likely voters, as illustrated by the higher numbers of “very favorable” and “very unfavorable” opinions expressed by respondents, which is to be expected at a time when the country is focused on the national health reform debate rather than on state-level issues. Notably, both figures are rated favorably by more than 50 percent of the electorate, which is good news for Democrats.

It’s true, Branstad’s favorability numbers eclipse Culver’s (and everyone else’s), but that isn’t much of a surprise. When a four-term governor leaves politics for 11 years, voters’ memories can become pretty selective. In 1990, ten years after Jimmy Carter lost the 1980 presidential election, the Georgia Democrat enjoyed a 67 percent favorability rating nationwide, compared to 62 percent for Ronald Reagan, who defeated Carter and served two terms. Does that mean that Carter would have won if he had run again in 1992? Probably not.

In state-level politics, name recognition is arguably the most important indicator of a candidate’s strength, not favorability.

If a candidate like Fong, whose name recognition is at 26 percent, wins the primary and hopes to close the gap with Culver, he will have to buy a lot of expensive statewide advertising just to introduce himself. Culver, who doesn’t need to introduce himself to voters, will be free to spend his advertising budget defining Fong negatively to the three fourths of the electorate that does not yet know him.

This dynamic puts lesser-known candidates at a significant disadvantage, and it may help explain why incumbents win re-election so often.

Of course, the election is a long way away, and a lot can change in a year. But as things stand now, Culver’s chances of winning a second term don’t look so bad. Branstad is Culver’s biggest threat simply based on name recognition, but opinions of him are likely to shift over the course of a protracted Republican primary.