Iowa City, Iowa (CNN) -- Katherine Valde is ready when a fellow student says "no thanks" to early voting because of the thrill of casting a ballot on Election Day.
"Things come up, you can have an exam," says Valde, the president of the University of Iowa Democrats.
"You can wait until Election Day and not know where your precinct is. A lot of students have to go to elementary schools around town, and they don't have cars, they don't really know where it is."
Truth is, Valde knows younger voters like herself are less reliable when it comes to turning out in the crunch, and "with early voting, it just gives us 40 more chances to catch people."
Valde led by example Thursday, waiting in line for more than an hour to cast her ballot on the first day of in-person early voting in Iowa.
The line at the Iowa City Public Library was dominated by Obama voters, as was a Des Moines polling place CNN visited as the doors opened Thursday.
Valde says the Obama campaign and state Democratic Party have urged her to keep checking her list and pushing students to vote now.
"If you vote early, it frees up campaign resources to talk to people who might be undecided," she told us as she waited patiently to vote.
Iowa is one of 35 states plus the District of Columbia that allow some form of early in-person voting. Of the nine presidential battlegrounds CNN now rates as tossups, only New Hampshire and Virginia do not have large-scale early voting.
In Iowa four years ago, early voting accounted for 36% of the ballots cast for president. In Johnson County, home of the University of Iowa, it was 55%, the highest of Iowa's 99 counties, and County Auditor Tom Slockett says demand for early ballots so far is up significantly from 2008.
And Democrats have a big early edge.
In Johnson County, requests for mail-in ballots as of Monday were running more than 12-1 in favor of Democrats. Statewide, as of close of business Wednesday, the Iowa Secretary of State's office said Democrats had a nearly 5-1 edge in making requests for absentee ballots.
Republicans here don't dispute the early Democratic advantage in ballot requests. But they promise to narrow the edge somewhat; the GOP's first mailing nudging Republicans to consider mail-in voting was sent just this week.
Iowa Republicans also suggest too much can be made of the early numbers, making the case that those voting before the presidential debates are hardcore partisans who were almost certain to vote eventually anyway.
"If you look at who is early-voting right now, absentee ballots, 80%, almost 90%, are 'four of four' voters, meaning they voted in the last four elections," veteran Iowa GOP strategist Steve Grubbs told CNN.
"So it's a difference of strategy. You put your money into the last three weeks or you put your money into early voting. The Republican Party will put a little more into the last three weeks, and the Democrats a little more into the first initial blast of early voting."
Grubbs said one effort in which Democrats were smart to focus so much early voting attention was younger voters.
"Four years ago there was a lot of enthusiasm among younger voters and everybody knows that has lessened," Grubbs said. "They have got to figure out the strategy to increase their early voting."
On the flip side, he said Republican Mitt Romney runs stronger among the state's elderly voters, who are among the most reliable to cast ballots.
More broadly, Grubbs conceded a modest Obama edge in Iowa at the moment and said there is nervous talk among some Republicans that Romney could hurt GOP candidates in competitive congressional and other races. In his view, such talk is premature.
"Clearly if a (presidential) candidate loses by more than five, it starts to affect down-ballot and that's a big issue for Republicans," Grubbs said. "The way I look at it, we are starting the fourth quarter. We have a strong quarterback. And anyone who knows football knows the fourth quarter is where most of the action happens. So October will be big; and if Romney has a good start to the month, we will be fine."
Iowa Republicans also say, despite the Democratic edge in early voting so far, that the GOP is breaking records in terms of its grassroots organizing.
At a Linn County phone bank in Cedar Rapids, volunteer Karen Zmoos (pronounced Smoose) is credited with making the millionth voter call in Iowa this cycle.
She is pleasantly working the phones again this week, and adding this question when a voter indicates support for the Romney-Ryan ticket: "Excellent. Would you be interested in voting early this election?"
Zmoos says Iowa's unpredictable winters make her a fan of early and absentee voting, and she shrugs off the early Democratic edge in absentee ballot requests as temporary.
"You know we are working hard here," Zmoos said during a quick break from working the phones. "We are rolling up our sleeves and putting our boots on, and we are going at it. We still have time."
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