Iowa Republicans have sunk a lot of time and resources into defeating longtime Democratic Rep. Leonard Boswell, and with winds at the GOPs back, this could be the year it pays off. But state Sen. Brad Zaun wasnt Republicans top choice, and after having trouble harnessing national and state momentum in his district, he has suffered a few costly stumbles.On Thursday the Des Moines Register reported that in 2001 while Zaun was mayor of Urbandale, a suburb of Des Moines, police had to ask him to leave an ex-girlfriend alone. The article alleged that Zaun, who was divorced then but is now married again, came to the womans home after midnight and pounded on her windows, calling her names. When he followed up with a phone call, a police officer answered and asked him not to contact her again. The article could not have come at a worse time. On the same day, Zaun took his previously scheduled turn on the Iowa State Fairs soapbox and was forced to offer a mea culpa in a press conference afterward.Regardless of Zauns weaknesses, Boswell cant get comfortable. He hasnt won more than 56 percent of the vote in his Des Moines-based district since before redistricting in 2000. Boswell, a 76-year-old farmer, has been dogged by rumors that hell retire and the suggestion that he has never quite fit his urban district. Since Democrats gained control of the House in 2006, Republicans have added the criticism that the Blue Dog is too close to Democratic leadership.Boswell sees those criticisms as nonsense and silly talk. For one thing, he said, hes younger than Sen. Chuck Grassley (R), who will turn 77 in September.I get up early, he said in a phone interview last week. Im the first one in the office when Im in D.C. Im usually the last one there at the end of the day.He counters the idea that his agrarian roots make him less qualified to represent Iowas largest city, pointing to his time living there when he served in the Legislature from 1984 to 1996, and he argues that moving into the majority naturally means voting with his party more often.Some will say youre with Pelosi too much, he said of Speaker Nancy Pelosi (D-Calif.). Excuse me, maybe Pelosis with me.Zaun, 48, wasnt the obvious choice to retire Boswell. In the seven-way June primary, former Iowa State University wrestling coach Jim Gibbons had celebrity, national endorsements and better fundraising numbers on his side. Yet Zaun won with 39 percent to Gibbons 26 percent, and he won the support of all his primary opponents within a few days. Though up-and-coming Republicans in past cycles have gotten national support and continued to fall just short, Zaun thinks he can close the gap.Everythings changed this time, he said in a phone interview last week. He cited the likely Republican year and his base in Polk County, where the bulk of the districts votes come from, as game-changers.