(CNN) -- Sens. Hillary Clinton and Barack Obama tried to convince Ohio voters they have what it takes to fix the economy as they campaigned before contests that could decide the Democratic presidential nomination.
Sen. Hillary Clinton is hoping to break Barack Obama's 11-contest winning streak.
Delegate-rich Ohio and Texas hold contests on Tuesday, along with Rhode Island and Vermont.
In Ohio, Clinton and Obama have been focusing largely on the economy and the North American Free Trade Agreement, which many Ohioans blame for the loss of manufacturing jobs.
"I've been around, doing this work for 35 years," Clinton -- fresh from an cameo appearance on "Saturday Night Live" -- told voters at Westerville North High School in suburban Columbus, Ohio.
"And I know what a difference it makes whether we have a president who gets up everyday in that White House and worries about what goes on in your lives, with your jobs and your health care and your families and your futures. That's the kind of president I will be."
Obama on Sunday spoke with voters in the rural southeast Ohio town of Nelsonville. He credited "green jobs" with helping "reduce dependence on foreign countries for oil," but said such towns face difficult economic times.
"I will be honest with you about the challenges we face, and creating economic development and jobs here in this community will be challenging," he said. "It's not going to be easy."
He added, "I'm hopeful about the future of all towns across Ohio and across the country that are struggling."
Clinton is banking on Tuesday's primaries to break the Obama's 11-contest winning streak. Even Clinton's husband, former President Bill Clinton, has suggested that if she does not win in Ohio and Texas, her campaign would face a dramatically difficult challenge overtaking Obama. Watch why the Democratic race may last seven more weeks »
A "poll of polls" calculated by CNN indicates competitive races in both states. The Texas poll of polls of likely primary voters has Obama with a slight lead over Clinton -- 47 percent to her 45 percent, while 8 percent said they were undecided.
In Ohio, the poll of polls showed Clinton at 48 percent, Obama at 43 percent and 9 percent undecided.
The Texas poll of polls averages five surveys conducted February 26 - March 1: American Research Group, Reuters/C-SPAN/Houston Chronicle/Zogby, MSNBC/McClatchy/Ft. Worth Star-Telegram/Mason-Dixon, Fox News/Opinion Dynamics and Belo/Public Strategies.
The Ohio poll of polls averages four surveys, also conducted February 26 - March 1: American Research Group, Reuters/CSPAN/Houston Chronicle/Zogby, Cleveland Plain Dealer/Mason-Dixon and Fox News/Opinion Dynamics.
Also on Sunday, Clinton supporter Sen. Dianne Feinstein of California and Obama supporter Sen. Dick Durbin of Illinois sparred over which candidate would respond best to a 3 a.m. phone call about a crisis -- a reference to a television advertisement the Clinton campaign launched Friday in Texas.
In the advertisement, a phone rings incessantly as video shows children asleep. "Your vote will decide who answers the call," a narrator says. "Whether it's someone who already knows the world's leaders, knows the military, someone tested and ready to lead in a dangerous world. It's 3 a.m. and your children are safe and asleep. Who do you want answering the phone?"
"The basic question is not whether the president can wipe the sleep out of his or her eyes and think clearly, but the judgment that they'll use once that phone call is understood," Durbin told "Fox News Sunday."
"And I think that Sen. Obama has met that test."
Feinstein lauded Clinton's experience. "I know Hillary is ready and tested," she said. "I believe she is ready for a 3 a.m. phone call, and I don't believe Iraq was a 3 a.m. phone call," she said, disputing an Obama charge that Clinton's "red phone moment" was her 2002 Senate vote that gave President Bush authority to invade Iraq.
"Iraq was essentially a considered judgment that was made, rightly or wrongly," Feinstein said. "It wasn't a missile on the way to the shores of the United States at three in the morning."
Durbin disagreed. "It was almost 2 a.m. on October 11, 2002, and that's when we were called on to vote as to whether to authorize President Bush to invade Iraq," he said.
"There were many senators who decided at that time to give the president the authority. Barack Obama said clearly he would not. His judgment was right at that critical moment in history. And I think it's judgment that people are looking for."
David Axelrod, Obama's chief strategist, and Howard Wolfson, Clinton's communications director, engaged in a spirited debate on ABC's "This Week," and criticized the other's funding.
"The Chicago Tribune has said, when they endorsed him, 'Come forward, Sen. Obama. Answer the legitimate questions. How many fundraisers? How much money raised? How much of it was given through straw donors?' " said Wolfson.
He also mentioned Obama's connection to indicted real-estate developer and political fund-raiser Tony Rezko, who has pleaded not guilty to federal charges of conspiracy, influence peddling and demanding kickbacks from companies seeking Illinois state business.
Rezko contributed to the campaigns of numerous Democrats, including Obama, who has not been accused of legal wrongdoing and has vowed to give up all related funds.
"We've answered those questions," Axelrod said. "As you know, we returned $150,000 ... as you returned $850,000 of Norman Hsu's," he added, referring to the Democratic fundraiser indicted last year on charges of fraud and violating various campaign finance laws.
Hsu had been a top contributor to Democrats, including Clinton and Obama. E-mail to a friend