Even Hollywood, seldom quick to portray Iowa as progressive, thought the state could elect a woman to Congress more than a half-century ago.

But 60 years after Billy Wilder's "A Foreign Affair" featured the character Phoebe Frost, a freshman congresswoman from Iowa, 2008 is yet another chance for Iowans to send their first woman to Capitol Hill.

"This is one of the great mysteries of life: Why hasn't Iowa elected a woman to Congress?" said Debbie Walsh, director of the Center for Women in American Politics at Rutgers University. "On the face of it, it doesn't make any sense."

The rate of Iowa women running for Congress has taken off in the past decade, with two hoping to break through in November. The increased frequency of female candidates, and Democrat Hillary Clinton's campaign for the Iowa presidential caucuses, are weakening what has been a stubborn barrier, observers say.

Still, political and cultural factors have worked against Iowa women in the nearly 50 years they have been running for Congress.

Iowa women have run for U.S. House or Senate 17 times, the first in 1962.

This year, Perry Democrat Becky Greenwald is challenging 4th Congressional District Republican Tom Latham, a seven-term House member from Ames.

The Democratic Congressional Campaign Committee has listed the 4th District, where registered Democrats narrowly outnumber Republicans, as an emerging race, although not a top-tier challenge. EMILY's List, an influential group that supports women who back abortion rights, endorsed Greenwald last month, elevating the race's significance.

Meanwhile, Ottumwa Republican Mariannette Miller-Meeks is challenging U.S. Rep. Dave Loebsack, a freshman from Mount Vernon, in the 2nd Congressional District. That district is less competitive, with registered Democrats outnumbering Republicans by roughly 60,000.

While 13 Iowa women have run for Congress in Iowa, Greenwald and Miller-Meeks are among 12 who have challenged sitting members of Congress.

Iowa State University political science professor Dianne Bystrom said one reason Iowa women have had a hard time is that challengers win roughly 5 percent of the time nationally, male or female.

"The best way to elect a woman to Congress in the state of Iowa is to run a woman in an open-seat race," said Bystrom, director of ISU's Carrie Chapman Catt Center for Women and Politics. "Better yet, run two women against each other."

Women have waged competitive challenges that often turned out to be ill-timed.

In 2002, Cedar Rapids Democrat Julie Thomas challenged Jim Leach in the 2nd District, after redistricting prompted the longtime Davenport Republican to move to Iowa City. Also that year, Bettendorf Democrat Ann Hutchinson challenged Republican Jim Nussle in the 1st District, which was altered after reapportionment to include the Quad Cities.

Both women were heavily recruited and received the backing of the DCCC and EMILY's List. But Thomas lost by 8 percentage points, while Hutchinson lost by 14 points in a year all five Iowa incumbents were returned to office.

Iowa is among four states never to have sent a woman to Washington, D.C., including Delaware, Mississippi and Vermont. When the office of governor is added, the list shrinks to just Iowa and Mississippi.

Women on both sides of the party divide express frustration and embarrassment about Iowa women's absence in Congress.

"I'm ashamed," said Sherry Lou Williams, a Norwalk Democrat. "Most states have elected women to these offices. We have good women, but many of them have chosen not to run. I think we're ready."

Celia Wright, a West Des Moines Republican, said she was doubly concerned, considering so few of the women who have run for Congress from Iowa have been Republicans.

"I care about it as a Republican and a woman both," Wright said. "I see the way the wind is blowing in Iowa and nationally and our women are not stepping up."

Miller-Meeks is just the third Republican woman to run for Congress from Iowa, and the first in more than 30 years.

As the Republican Party has become more socially conservative over the last 30 years, it has shed some women who support abortion rights. That has contributed to an imbalance where about two-thirds of women elected to Congress and state legislatures around the country are Democrats, and about a third Republicans.

Still, Iowa's political environment for women is considered average among states, based on several factors, Bystrom said.

About 22 percent of Iowa's state representatives and senators are women, ranking the state 26th in the nation.

Iowa also has had a total of four female lieutenant governors, all consecutively since 1987. The 21-year stretch is the longest for the office in the nation's history.

But other cultural factors work against Iowa electing a woman to Congress.

One is states that tend to elect women are more urban than rural. Despite the growth in Des Moines' suburbs, Iowa remains vastly rural.

Likewise, states with younger and growing populations tend to elect women. Iowa is among the nation's oldest states and grew by the sixth-slowest rate in the nation from 2000 to 2005.

States prone to electing women also tend to be more politically liberal and less religiously fundamentalist. Iowa is a politically balanced state, although voter registration and voting trends have favored Democrats in the past four years.

Thirteen of the 17 times Iowa women have run for Congress were from 1992 to present. The rate is more than all the women who ran for Congress from Delaware, Mississippi and Vermont combined during that period. Also, five times during those 16 years, women have run in more than one Iowa congressional race.

Clinton's yearlong effort last year in Iowa has had a practical and philosophical impact that could help a female candidate break through, some of Clinton's leading Iowa supporters said.

Des Moines Democrat Andie McGuire, who said she would consider running for Congress sometime, said campaign volunteers who supported Clinton had joined Greenwald's race.

Clinton noted before her third-place caucus finish that Iowans had never sent a woman to Washington, as a way of lowering expectations.

Still, her frequent presence in the state as a U.S. senator and a leading candidate for the Democratic nomination left an impression in voters' minds, said Des Moines Democrat Bonnie Campbell, who was Clinton's Midwest campaign chairwoman.

Campbell, the only woman to be elected Iowa attorney general, failed to break the glass ceiling to the governor's office in a 1994 run against the incumbent, Republican Terry Branstad.

"I just know it has to have an impact, that Hillary ran, and that she ran so well and that she was strong and smart and tough," said Campbell. "There is no doubt in my mind her candidacy has left a legacy of commitment to electing an Iowa woman to Congress."