CRESTON, Iowa — As the sun lowered behind a nearby barn, US Representatives Tom Latham and Leonard L. Boswell nipped at each other with unconcealed disdain fomented through months of negative advertisements and campaign miles.
The setting, a tiny radio station more or less in an open field, could not have felt farther from Washington and the race for the presidency.
But the two men, locked in one of the hardest-fought House races in the country, are finding their campaign inextricably tied to the race for the White House, as Iowa emerges as one of the most contested states between Mitt Romney and President Obama. Last week, Latham, a Republican, appeared with Romney at a rally near Van Meter, and former president Bill Clinton came to Des Moines to stump for Boswell, a Democrat.
Boswell, who has struggled to raise money, is depending on Obama’s extensive operation here, which exceeds Romney’s, to pull him along.
‘’I would say his campaign has an impact on mine,’’ Boswell said.
Latham, in contrast, has generally labored to keep his campaign largely independent from the fight for the White House, no doubt hopeful that if Romney fails to win Iowa, he can still prevail in his own southern part of the state.
‘‘I don’t see Governor Romney getting more of the vote than I would here,’’ Latham said. ‘‘Some undecided people are going with us.’’
Latham’s positioning reflects not only what is needed to win independent voters in his district, but also the problem Romney has created for some Republicans in Iowa with his opposition to subsidies for wind power, a major economic force here. Latham has openly disagreed with Romney on the tax break.
Redistricting, which cost Iowa one of its five House seats, has left these two long-serving incumbents vying for a new district that has been configured with roughly the same number of Republicans, Democrats, and independent voters and stretching through a rural area from Des Moines to Nebraska.
For all its local vigor, this race has been a remarkable mirror of the federal campaign, with massive spending by outside groups, murky polling data, and escalating nastiness.
Just as many voters in swing states remain undecided about the presidential race, interviews with voters in Des Moines — the heart of Polk County, where both sides believe this race will be won — show that some hyper-informed voters from both parties are torn about this election, too.
Boswell ‘‘has done a lot of great things over the years,’’ said Patrice Maurer, an independent voter who works as a fund-raiser for a nonprofit. She said she believes that Boswell would be more favorable to nonprofits than Latham.
But Latham did a lot to save the 132d Fighter Wing of the Iowa Air National Guard, she added. She is torn, unnerved even.
‘’I am going to vote,’’ Maurer said, but for whom, who knows. She is also undecided about the presidential race.
Boswell has an advantage: Des Moines is in his current district. Further, his campaign hopes he will benefit from the nearly 30,000 ballots cast by Democrats so far in early voting, versus roughly 16,500 by Republicans.
But at 64, Latham is younger (Boswell is 78), has more money, and has a slight edge in Republican registration in the district.
‘’My hunch is that it is more possible for both President Obama and Congressman Latham to win than it is for governor Romney and Congressman Boswell to win,’’ said Chuck Offenburger, who runs a website with a focus on Iowa, citing those factors.
Boswell, he allowed, ‘‘is better known across the district than Latham,’’ and ‘‘does have a proven record of winning in past races where he looked like he was whipped. But Latham is younger, a handsome devil, and is actually a moderate, as Iowa Republicans go. People in Des Moines and across southwest Iowa will be comfortable aligning with him.’’
In fact, both men are moderates vis-a-vis their parties in Iowa, though Latham now tries to paint Boswell as Obama’s policy handmaiden, and Boswell takes delight in mentioning Latham’s friendship with House Speaker John A. Boehner of Ohio, repeatedly implying that somehow their shared taste for cigarettes and golf should have produced a farm bill.
‘‘I’ve always had crossovers,’’ Boswell said, referring to voters. ‘‘I’m not far left or far right.’’
Given their more than 30 years of combined experience in the House, the two candidates tend to argue over their legislative records, sometimes going back to the mid-1990s to argue the fine points of what a voucher is.
Often these debates circle back to the White House race. For instance, Latham enjoys pointing out that Boswell supported the president’s health care law, and Boswell, unlike some other Democrats, is unapologetic.
‘’I did!’’ he interjected in one debate, to emphasize it.
Latham also tries to blame the White House for the stalemate over the farm bill, which House Republicans have refused to bring to the floor, saying that the administration has ‘‘not said a word on what their position is’’ on the bill.
Boswell will happily campaign with anyone from the administration, which some Democrats avoid.
‘‘We talk frequently,’’ he said of Obama’s campaign. ‘‘Joe Biden was in Council Bluffs and I was included.’’
Then there is the money game. Latham more than doubled Boswell’s fund-raising from July through September, and began October with $1.5 million, nearly five times as much as Boswell reported Monday.
That advantage will probably give Latham more spending flexibility during the final days of the campaign.
Boswell will need any boost he can get from Obama’s extensive advertising campaign and get-out-the-vote operations.
‘’I think I’m going back to Congress,’’ he said.
Latham says the same about himself.
Only one will be right.