Vice President Joe Biden and Rep. Paul Ryan faced off Thursday night in their one and only match-up.

The debate, which was moderated by ABC News correspondent Martha Raddatz, started off with foreign policy.

Republican Paul Ryan slammed the Obama administration in the vice presidential debate for failing to call the attack on a U.S. consulate in Libya a terrorist attack.

Vice President Joe Biden responded by criticizing Ryan and Republican presidential candidate Mitt Romney for launching political attacks before they knew the facts on the ground.

Ryan says the U.S. is witnessing the unraveling of President Barack Obama's foreign policy. He says the attack that killed U.S. Ambassador Chris Stevens shows the U.S. is projecting weakness abroad.

Biden says that's, quote, "a bunch of malarkey.'' He says the U.S. will bring those responsible to justice and ensure any mistakes aren't repeated.

The vice president says Obama has led with a steady hand and clear vision, and that Romney would do the opposite.

The foreign policy portion of the debate continued with Iran. Biden said his administration has the toughest sanctions in history on Iran, even as his Republican rival says the White House has no credibility on the issue.

Ryan said Thursday evening that President Barack Obama has allowed Iran to get four years closer to building a nuclear weapon.

The debate also touched on Medicare and Social Security.

Biden and Ryan are clashing over their plans for Medicare and Social Security, government programs for seniors.
Biden says he and Obama would never sign onto the sort of voucher program proposed by Ryan and Romney. Ryan fired back that the Republican plan would give seniors more choice in their medical care.

Romney's plan would introduce undetermined subsidies to help future retirees buy private insurance or join a government plan modeled on traditional Medicare. Obama's health care law cuts Medicare spending for hospitals and other providers by more than $700 billion over a decade. Those cuts are being used to provide health insurance to more working-age Americans.

The debate continued to heat up as the men addressed the topic of taxes.

Ryan says there aren't enough rich Americans to tax to pay for all of Obama's spending.

"Watch out, middle class," Ryan said. "The tax bill is coming to you.''

Ryan says he and Mitt Romney want to give Congress a framework for taxes that involves lowering rates by 20 percent. He says he guarantees that can be paid for by closing loopholes, mostly on the upper class. But he isn't saying which loopholes he'd close.

Biden says the only way to pay for Romney's plan is to raise middle-class taxes. He says Republicans insist on needless tax cuts for the rich and are holding hostage middle-class tax cuts that Obama wants to make permanent.

Thursday's debate comes after the first presidential debate between President Barack Obama and Republican contender Mitt Romney.  Obama has admitted that he didn't bring his A-game to that debate.

Information from the Associated Press was used in this report.