Newark, Delaware (CNN) -- A feisty Christine O'Donnell attacked her Democratic opponent but also stumbled in Wednesday's debate with Chris Coons in their election battle for Delaware's U.S. Senate seat held for nearly four decades by Vice President Joe Biden.
The highly anticipated showdown between two candidates considered surprise contenders featured O'Donnell displaying her conservative credentials that gained Tea Party backing while Coons, put on the defensive at times, generally backed Democratic policies favored by President Barack Obama.
O'Donnell's primary victory over a veteran mainstream Republican candidate last month shook up the GOP establishment, with party strategist Karl Rove even questioning her qualifications. Now trailing badly according to the latest polls, she appeared nervous at the start but quickly went on the attack, accusing Coons of raising taxes and offering a "rubber stamp" to Obama administration policies if elected.
"My opponent wants to go to Washington and rubber-stamp the spending bills" that she said are hurting the nation and Delaware. Later, O'Donnell said, a vote for Coons would cost the average Delawarean $10,000 "instantly" in tax hikes and energy reform costs.
At other times, her attacks were less precise and drew scorn from Coons, such as when she said the influence of a Marxist college professor on Coons' political beliefs should "send chills up the spine of every Delaware voter."
"If it were accurate, if it were true, I'd agree," Coons responded. "It's not accurate and it's not true."
He emphasized his experience as New Castle County executive but also attacked O'Donnell, calling some of her positions extreme and accusing her of lying about his record in campaign messaging.
"Most of them are untrue," Coons said of claims about him on her campaign website. "Some of them are just flat-out lies, some of them are mischaracterizations, some of them are just factually untrue."
Both candidates framed the election as a clear choice for voters, and their stance on issues showed that.
Coons said he supports abortion rights and embryonic stem cell research while opposing the ban on openly gay and lesbian soldiers from military service, and he backed most Obama administration policies, with a few refinements. For example, he said Bush-era tax cuts should be extended to the vast majority of the county but questioned Obama's plan to limit the extension to those families making up to $250,000 a year. He also said the health care reform law needed some adjustments.
O'Donnell backed Republican positions such as calling for tax cuts and spending cuts to balance the budget, and she repeatedly said tough social issues such as abortion rights and teaching creation theory in public schools should be state or local issues instead of federal decisions. When pressed on a comment from more than decade ago when she questioned evolution theory, she responded: "What I believe is irrelevant. What I will support in Washington, D.C., is the ability of the local school system to decide what is taught in their classrooms."
In one testy exchange, O'Donnell referred to Obama administration policies creating what she called "a culture of dependency" by expanding the number of people getting food stamps. Coons immediately tried to portray her as insensitive saying: "To simply denounce people as being dependent because they're applying for and receiving food stamps in the worst recession in modern times is frankly slandering people who are in incredibly difficult times."
O'Donnell interrupted, saying, "That's not fair. That's not fair of you to say that because that's not at all what I'm doing," and then counter-attacking by declaring: "I'm not the person who would cut the tax benefits of disabled and low-income citizens as you did as county executive."
The most serious problem for either candidate came when O'Donnell was asked to cite any specific recent Supreme Court rulings that she opposed.
"Oh gosh, give me a specific one," she said, and when told the question required her come up with cases, O'Donnell responded, "I'm sorry," and promised to put the information up later on her website.
Coons quickly referred to the Citizens United ruling in January in which the court lifted some limits on corporate contributions to campaign spending.
The debate produced a few humorous moments, such as when Coons said O'Donnell's well-publicized statements from a decade earlier that she dabbled in witchcraft and questioned evolution theory were distractions instead of a substantive campaign issue.
"You're just jealous that you weren't on 'Saturday Night Live'," O'Donnell said, referring to the comedy show's satirical skit about her.
"I'm dying to see who's going to play me," Coons responded with a smile.
O'Donnell scored a major upset last month when she defeated Rep. Mike Castle to win Delaware's GOP Senate nomination. She had support from the Tea Party Express, a major endorsement from former Alaska Gov. Sarah Palin, as well as the strong anti-establishment and anti-incumbent feelings among voters this year in topping Castle, a moderate Republican who served nine terms in the House and eight years as governor before that.
However, her victory made a race considered relatively safe for Republicans based on the expected nomination of the popular Castle into one in which the little-known Coons suddenly became the favorite, due to O'Donnell's inexperience and questions about her past.
Since O'Donnell's primary victory, she has had to deal with controversial and colorful comments she made about a decade ago when she was a spokeswoman for conservative causes.
Her first campaign commercial began with O'Donnell declaring, "I am not a witch" in response to her statement years ago on the program "Politically Incorrect" that she "dabbled in witchcraft."
She acknowledged in an interview with CNN that the resurfaced clips have forced her to reinvent herself in the final weeks of the campaign.
"I haven't been embarrassed. And I'm not saying that I'm proud," O'Donnell told CNN's Jim Acosta last week. "I've matured in my faith. I've matured in my policies. Today you have a forty-something woman running for office, not a 20-year-old. So that's a big difference."
The debate at the University of Delaware in Newark was co-moderated by CNN's Wolf Blitzer and by longtime Delaware news anchor Nancy Karibjanian of Delaware First Media.
Results of a CNN/Time/Opinion Research Corp. survey released Wednesday showed Coons with a 19-point lead over O'Donnell. However, O'Donnell enjoys a lead in campaign cash, which is one reason both President Barack Obama and Biden are coming to Delaware on Friday to help Coons raise money.
O'Donnell, 41, ran unsuccessfully for Senate twice before, in 2006 and 2008. Since winning the primary, she's had to deal with controversies involving unpaid income taxes and allegations of misusing campaign donations, as well as attacks from Democrats and some Republicans, including Rove, on her qualifications.
Coons, the 47-year-old executive of New Castle County, the state's most populous county, faced no serious opposition in the Democratic primary.
While he is running his first statewide campaign, Coons is neither a political novice nor a party outsider. In 1988, Coons served as a policy researcher for the failed Senate campaign of then-Lt. Gov. S.B. Woo.
He went on to earn a degree from Yale Law School, as well as a master's in ethics from Yale Divinity School.
The winner in November will fill out the remaining four years of Biden's final term in the Senate. Biden stepped down from his seat after his election in November 2008 as vice president.
Former Biden aide Ted Kaufman was named as an interim replacement, and did not seek a full term.
CNN's Tom Cohen, Paul Steinhauser, Jim Acosta, and Bonnie Kapp contributed to this report.