(CNN) -- A combative debate Thursday between Vice President Joe Biden and Republican challenger Paul Ryan came down to the issue of trust.
The running mates to President Barack Obama and Republican Mitt Romney in next month's presidential election each challenged the other's facts and claims in the 90-minute nationally televised debate that was their only showdown of the campaign.
Ryan repeatedly criticized the Obama administration as taking the nation in the wrong direction by hindering economic recovery and weakening its influence around the world.
"We're heading in the wrong direction," Ryan said of the administration's economic polices. "This is not what a real recovery looks like."
He also repeated several times, in reference to the recent terrorist attack on a U.S. diplomatic compound in Libya and other anti-American protests, that "what we are watching on our TV screens is the unraveling of the Obama foreign policy."
Biden called several of Ryan's remarks "malarkey" and challenged Americans to trust their common sense when judging proposals by the Republican challengers.
The tax and entitlement reforms proposed by Romney and Ryan would harm the middle class and favor the wealthy, Biden said in seeking to depict Republicans as protectors of the privileged.
"You think these guys are going to go out there and cut those loopholes?" Biden asked about unspecified moves by Romney and Ryan to balance tax cuts they promise.
On the topic of reforming the Medicare program for senior citizens, which Romney and Ryan seek to partially privatize, Biden referred to a Ryan proposal to provide partial government payment for seniors in the future to buy private health care.
"Folks, use your common sense. Who do you trust on this?" Biden said, saying Ryan's plan would increase Medicare costs to recipients by $6,000 a year. Ryan disputed the claim, which was based on a proposal that he has since altered.
The debate before the November 6 election pitted Biden, 69, and his almost four decades of experience in national politics against the 42-year-old Ryan, a 14-year congressional veteran who rose to the chairmanship of the powerful House Budget Committee.
Despite Biden's more extensive experience, CNN polling showed 55% of respondents expected Ryan to win the debate, and both campaigns tried to downplay expectations for their candidate ahead of time.
Privately, senior Democrats told CNN they believed a strong showing by Biden could help the Democratic ticket, but wouldn't be enough to erase problems created by Obama's lackluster performance at last week's first of three presidential debates.
Obama and Romney will square off again on October 16 in New York and October 22 in Florida.
Polling after the first presidential debate showed Romney tightening the race nationally and in some of the nine battleground states considered vital to either candidate's chances for winning the necessary 270 electoral votes.
Ryan repeatedly sought to focus the debate on the Obama-Biden record of the last four years, arguing the administration's policies hindered economic recovery and weakened the nation's standing and influence in the world.
For his part, Biden tried to frame the election as a choice between differing directions for the country by contending policies of the Romney-Ryan ticket would hurt the middle class and move the nation backward on social issues such as gay rights and abortion.
Martha Raddatz of ABC News aggressively moderated the debate, challenging both candidates on some claims and moving on to various topics covering both domestic and foreign policy.
Ryan, the conservative congressman from Wisconsin, criticized Obama's administration for its failure to protect four Americans killed in the Libya attack last month, and for mixed messages about what transpired.
"This Benghazi issue would be a tragedy in and of itself. But unfortunately it's indicative of a larger problem," Ryan said, adding that illustrated an unraveling of the administration's foreign policy.
Biden smiled and shook his head as Ryan delivered his criticism, then responded that "not a single thing he said was accurate."
On Iran, widely backed international sanctions pushed by Obama and backed by allies have devastated the Tehran economy, Biden said. He also rejected assertions that Obama wasn't working closely with Israeli Prime Minister Benjamin Netanyahu, and that the United States wasn't fully committed to making sure Iran doesn't require a nuclear weapon.
"This president doesn't bluff," Biden said.
Ryan, however, insisted that Iran was closer now to having a nuclear weapon than it was four years ago, blaming the administration for allowing that to happen. He bluntly said that Tehran could not become a nuclear power.
"This is the world's largest sponsor of terrorism," he said. "And if they get nuclear weapons, other people in the neighborhood will pursue nuclear weapons as well. We can't live with that."
On the economy, Biden blasted remarks from Romney in which the Republican presidential nominee described 47% of Americans as Obama supporters who saw themselves as "victims" and dependent on government.
"He's talking about the people who built this country," Biden said. "All they're asking for is a fair shot."
Ryan countered by citing the unemployment rate for Biden's hometown of Scranton, Pennsylvania: 8.5% in January 2009 and 10% today. And he said that story is playing about nationwide.
"That's not how it's going," Biden jumped in, speaking of the national unemployment rate. "It's going down."
The Delaware Democrat is hoping to inject new energy into his party's ticket following last week's presidential face off where Romney outperformed Obama.
Viewers and pundits from both parties hailed Romney's aggressiveness as the former Massachusetts governor tore into Obama on the sluggish economy and other issues, forcefully challenging the incumbent's policies.
Obama was chided for being passive. He said he was too polite. Polls conducted after the debate indicate the White House race is now extremely tight ahead of the election.
Key surveys indicate that Obama and Romney are knotted up in the battleground states of Virginia, Florida, Ohio, Wisconsin and Colorado. Most experts believe that nine swing states will determine the next president.
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