Hillary Clinton’s rivals for the Democratic presidential nomination sought Wednesday to leverage their standing with Iowa voters based on a 2012 email written by the former secretary of state in which she characterized caucuses as "creatures of the parties' extremes."

In radio interviews broadcast across Iowa, when asked about Clinton's email, both Sen. Bernie Sanders (Vt.) and former Maryland governor Martin O’Malley voiced appreciation for Iowa’s first-in-the-nation caucuses and the party activists who participate in them.

Sanders told the Radio Iowa network that other states "have something to learn" from Iowa, adding: "I have been deeply impressed at how the people of Iowa take their responsibilities very, very seriously, ask important questions and spend a lot of time understanding where the candidates are coming from."

O’Malley, who’s running a distant third in the state behind Clinton and Sanders, threw sharper elbows, telling the same radio network: “Secretary Clinton’s had a long-strained relationship with Iowa. I think she’s been disappointed in the past by not prevailing in the caucuses, and perhaps that’s why she still feels the way she does.”

O’Malley was referring to Clinton’s third-place finish in the state’s Democratic caucuses in 2008 behind then-Sen. Barack Obama (Ill.) and former senator John Edwards (N.C.).

States with caucuses generally have lower turnouts than those with primaries. In Iowa, those who participate in the caucuses show up at a set time in the evening and can expect to spend a few hours participating.

Clinton’s characterization of caucuses was included this week in the latest 7,800 pages of emails released from her tenure at the State Department, where her use of a personal server has been a great source of controversy. In one email, Clinton writes to adviser Sidney Blumenthal about the nature of caucuses generally and does not single out Iowa.

Speaking of the status of the Republican race in 2012, she asserts that if GOP hopeful Mitt Romney can’t beat Newt Gingrich in Florida, “there will be pressure on state Republican parties to reopen or liberalize ballot access especially in the caucuses, which as we know are creatures of the parties’ extremes.”

In a statement Wednesday, Clinton’s spokeswoman in Iowa, Lily Adams, said that from the outset of her 2016 campaign, Clinton has been “committed to earning the support of every Iowan in February’s caucus.”

“Any suggestion otherwise is just flat out wrong,” Adams said. “That's why she made her first stop of this campaign in the Hawkeye State and why she continues to meet with Iowans in town halls, coffee shops and living rooms to discuss her plan to build an America where everyone can get ahead."

A poll last month by Quinnipiac University found Clinton leading Sanders in Iowa, 51 percent to 42 percent, with O’Malley registering at 4 percent.

Aides noted that Clinton has been endorsed by 28 state legislators in Iowa, 25 Democratic county chairmen and 18 mayors. She plans to return to the state to campaign on Friday.

In O’Malley’s interview with Radio Iowa, which has more than 50 affiliates across the state, he praised those who participate in the state’s caucuses as “people who care very passionately about our country.”

“They have a lot of different opinions, and perhaps if Secretary Clinton were out, going county-to-county, she’s see that herself,” O’Malley said.

During the 2008 presidential race, in which O’Malley backed Clinton over Obama, the then-Maryland governor sounded a more skeptical note about caucuses.

“If I had my wish, I wish that every state had a primary so more people could vote rather than had caucuses,” O’Malley said during an appearance on ABC News’s “This Week.”

“I’m biased toward primaries,” he said.

George Appleby, a Des Moines lawyer serving as chairman of O'Malley's Iowa campaign, noted that he worked with O'Malley on the campaign of Gary Hart during the 1984 caucuses.

"He knows first hand what a critical role [caucuses] play in the nominating process," Appleby said of O'Malley. "He's the only candidate in this race that has personally worked the caucuses, he's spent the most time in Iowa of any candidate, and he's campaigning the Iowa way."