DANVILLE, Ky. -- At odds early and often, Joe Biden and Republican Paul Ryan squabbled over the economy, taxes, Medicare and more Thursday night in a contentious, interruption-filled debate. "That is a bunch of malarkey," the vice president retorted after a particularly tough Ryan attack on the administration's foreign policy.

"Not a single thing he said is accurate," Democrat Biden declared after Ryan said U.S. Ambassador Chris Stevens had been denied sufficient security by administration officials. Stevens died in a terrorist attack on the U.S. Consulate in Benghazi on Sept. 11.

Both men seemed primed for a showdown from their opening moments on stage, and neither seemed willing to let the other one have the final word.

"I know you're under a lot of duress to make up for lost ground, but I think people would be better served if we don't interrupt each other," Ryan said to his older rival at one point. But both continued to do so — and interrupted moderator Martha Raddatz of ABC as well.

The debate took place a little more than a week after President Barack Obama and Republican challenger Mitt Romney met in the first of their three debates — an encounter that has fueled a Republican comeback in opinion polls.

With Democrats eager for Biden to show the spark the president lacked, he did so.

Unprompted, he brought up the video in which Romney had said 47 percent of Americans pay no federal income tax, view themselves as victims and do not take responsibility for their own lives.

"It's about time they take responsibility" instead of signing pledges to avoid raising taxes, Biden said — of Romney, Ryan and the Republicans.

But Ryan quickly turned to dreary economic statistics — 23 million are struggling to work, he said, and 15 percent of the country is living in poverty. "This is not what a real recovery looks like."

Medicare was a flashpoint, as well. Ryan said Obama's health care plan had diverted $716 billion from the program for seniors and created a new board that could deny care to patients who need it.

Democrats "haven't put a credible solution on the table," he said. "They'll tell you about vouchers. They'll say all these things to try to scare people."