Republicans claim that Democrats need to rack up an even bigger early vote tally this year because Election Day voters and independents are likely to break for Romney in greater numbers than they did for McCain.
Like Democrats, Republicans are outperforming their 2008 early vote totals, and Romney officials in Boston and Washington point out that more Republicans have voted early this year than in 2004, when Bush had a famously mobilized conservative base behind him.
But Republicans in Iowa wave off squabbles about vote tallies and make a simpler argument: Organization is no match for enthusiasm, and the currents have been moving in Romney's direction for weeks.
Republicans working on other state races say their internal polling shows movement toward Romney that began after the first debate on October 3 and has climbed steadily ever since.
Kraig Paulsen, the Iowa House Republican leader, said Romney's poll numbers have perked up in almost every one of the competitive statehouse districts he is monitoring.
'I'm seeing Gov. Romney picking up speed'
"I'm seeing Gov. Romney picking up speed in these races I am watching," said Paulsen, who is presiding over the GOP effort to recapture control of the lower chamber. "The low point in my data was somewhere around the start of the month, but since then it's just been a solid trajectory coming up."
The turnaround in Romney's fortunes is eye-opening.
After sewing up the Republican nomination last spring following a trying primary battle, Romney was in dismal shape in Iowa.
Most surveys showed Obama maintaining a comfortable lead over his rival throughout the spring and summer.
By late summer and early fall, Republicans here were settling in for an all-but-certain defeat and looking to refocus their efforts on a slate of down-ballot campaigns, particularly the two competitive House races in Iowa's newly drawn third and fourth Congressional districts.
A Wall Street Journal/NBC/Marist poll released Sept. 20 painted a grim portrait for the Republican nominee.
Half of the state's likely voters had an unfavorable opinion of Romney, and more than a third of evangelicals viewed him negatively. He trailed Obama by 10 points among independents, and by a staggering 18-point margin among women.
The dynamic changed dramatically, as it did in every battleground state, after Romney's shining debate performance in Denver.
Bob Vander Plaats, one of the state's leading evangelical voices who has often feuded with Iowa's Republican establishment, said he finally cast an early vote for Romney sometime after the second presidential debate.
Vander Plaats, who sided with Rick Santorum in the Iowa caucuses, said it took several months for Romney and his campaign advisers to soothe conservative Christian anxieties about the candidate's convictions on the issues of abortion and same-sex marriage.
Vander Plaats had a July conference call with three Romney officials in Boston to talk through some of his concerns.
"They said they were taking our issues seriously," he said.
Ryan selection helps with state's evangelicals
Romney's selection of Wisconsin Rep. Paul Ryan, a fervent abortion opponent, as his running mate helped stir support among evangelicals in the western part of the state and conservatives Catholics in the east.
The debate finally crystallized the choice for grassroots conservatives, who will show up without hesitation on Election Day, Vander Plaats said.
"There is no doubt that I wasn't the biggest Romney fan, but campaigns come down to choices, and I believe he is the much better choice in this campaign than Barack Obama," he said.
Republicans expect to lose the early vote but are planning to run up the score next Tuesday in the new fourth congressional district, where conservative icon Steve King has organized a dedicated network of volunteers in his race against Democrat Christie Vilsack.
Romney also hopes to cut into Obama's natural base of support in the working class counties and cities along the Mississippi River, where the president sailed to victory four years ago.
Yard signs are an imprecise way to measure enthusiasm, and some campaign operatives consider them a waste of money. But it is possible to make the drive from Des Moines to Dubuque, a 200-mile stretch of farmland along interstate 80 and highway 151 that was painted Obama-blue in the 2008 election, without seeing a single Obama sign or poster.