The lower-polling Republican candidates took aim at Hillary Clinton, the media and the GOP establishment at the first of two primary debates Thursday night – with Carly Fiorina launching a fiery attack against the Democratic front-runner.

Fiorina went after Clinton on everything from Benghazi to her email scandal to husband Bill Clinton.

“She is trying for the White House, she’s probably more qualified for the big house … She’s escaped prosecution more times than El Chapo. Perhaps Sean Penn should interview her. The woman should be prosecuted,” Fiorina said. 

She even took a swipe at the Clinton marriage, saying of Bill Clinton, “If my husband did what Bill Clinton did, I would have left him long ago.”

While Fiorina was forceful on stage, the surprise of the evening might have been former Virginia Gov. Jim Gilmore, whose unexpected return to the GOP debate stage also grabbed him some much-needed attention on social media.

Gilmore, who only started campaigning in Iowa this week, delivered a one-two Donald Trump punch. Gilmore said he's “the only veteran in this race” and then criticized Trump for holding a “faux” veterans fundraiser across town. He also staked out his positions on security and other matters. 

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The attacks were all part of an aggressive evening debate, preceding the prime-time debate with seven higher-polling candidates. 

Rick Santorum also lashed out at the media Thursday for its slim coverage of low-polling candidates like himself -- and extensive coverage of Trump -- during the Fox News/Google evening debate in Iowa.  

Santorum took issue with the fact that lower-polling candidates were not given the same amount of air time and said Iowans should vote for someone who would work for them, “not entertain them” – referring to Trump. 

Despite that comment, Santorum later said he would not attack other candidates. 

Santorum also objected to the use of the term "undercard" to describe the evening debates, and said all candidates deserve to be heard on "equal footing." 

Santorum, alongside Fiorina, former Arkansas Gov. Mike Huckabee and Gilmore, squared off in Des Moines in search of a game-changing moment. 

Fiorina also attacked the media for its coverage of the debates and called for citizens to “take our country back.”

"The establishment thinks they own this country, the pundits think they own this country, the media thinks they own this country," Fiorina said.

Fiorina defended her record running Hewlett-Packard, which has come under intense scrutiny. She called it a “tough time” for the technology industry and said she had to “make some tough calls.”

Huckabee fired off on Vermont Sen. Bernie Sanders – a presidential contender who calls himself a “Democratic socialist.”

“I honestly don’t understand how anybody with (an) IQ above plant life would honestly think that we would be better off if we let the government have all of the private property and that the government would dole out what they thought we should have,” he said. “I’m not feeling the Bern.”

Thursday’s debate is the final one before Monday’s Iowa caucuses.

Two candidates – Santorum and Huckabee -- are themselves past Iowa caucus winners. 

But Santorum, who won the caucuses four years ago, has struggled this time around to strike a chord with voters. So has Huckabee, who won the contest in 2008. The crowded Republican race has instead been dominated in the state by Donald Trump and Texas Sen. Ted Cruz. 

Instead of sold-out venues, Santorum spent Wednesday chatting up members of the Red Hat Society at Mason City Pizza Ranch. Santorum told reporters at the event he was fine with a smaller crowd.

“The next stop, there may be five,” he said. “And I’m okay with that. We’ll just do whatever we can to get in front of as many people as we can and hopefully make a difference out there.” 

This was Gilmore's first time on any debate stage in months. 

He appeared in the very first evening debate back in August -- but failed to qualify for the next five. He scored 1 percent in a recent Fox News poll, which qualified him for Thursday’s first matchup of the evening.

Gilmore had not appeared in Iowa to campaign until a week ago.

Following the debate, Huckabee and Santorum say they'll head to Trump’s “special event for veterans” rally in Des Moines. Trump, who is the GOP frontrunner, said earlier this week he would not attend the Fox News main stage debate.

Gilmore said he would not attend.

“I’m not going to attend any Donald Trump [event] across town, on any sort of faux veteran sort of issue.”