DANVILLE, Ky. — At odds early and often, Vice President 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.

“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 later to his rival, referring to Democratic pressure on Biden to make up for President Barack Obama’s listless performance in last week’s debate with Mitt Romney.

There was nothing listless this time as the 69-year-old Biden sat next to the 42-year old Wisconsin congressman on a stage at Centre College in Kentucky.

Ninety minutes after the initial disagreement over foreign policy, the two men clashed sharply over steps to reduce federal deficits.

“The president likes to say he has a plan,” Ryan said, but in fact “he gave a speech” and never backed it up with details.

Biden conceded Republicans indeed have a plan, but he said if it were enacted, it would have “eviscerated all the things the middle class care about.”

The debate took place a little more than a week after Obama and 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.

The serial disagreements started immediately after the smiles and handshakes of the opening.

Ryan said in the debate’s opening moments that 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.

“Not a single thing he said is accurate,” Democrat Biden shot back.

Republicans and Democrats alike have said in recent days the presidential race now approximates the competitive situation in place before the two political conventions. The two men are generally separated by a point or two in national public opinion polls and in several battleground states, with Obama holding a slender lead in Ohio and Wisconsin.

Both the president and Romney campaigned in battleground states during the day before ceding the spotlight to their political partners for the evening.

In Kentucky, Biden and Ryan seemed primed for a showdown from their opening moments on stage, and neither seemed willing to let the other have the final word. They interrupted each other repeatedly — and moderator Martha Raddatz of ABC as well.

Medicare was a flashpoint. 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.”

Biden quickly said that Ryan had authored not one but two proposals in which seniors would be given government payments that might not cover the entirety of their care. Otherwise, he said, the Romney-Ryan approach wouldn’t achieve the savings they claimed.

Unlike Obama, Biden had no qualms about launching a personal attack on Romney.

After Ryan argued that Romney’s plan would pay for reduced tax rates by eliminating tax loopholes for the wealthy, Biden noted that on a recent interview on CBS’ “60 Minutes,” Romney defended the 14 percent tax rate he pays on his $20 million income as fair, even though it’s a lower rate than some lower income taxpayers pay.

“You think these guys are going to go out there and cut those loopholes,” Biden asked, addressing the TV audience.

Across 90 minutes, the two men agreed precisely once.

That was when Ryan, referring to the war in Afghanistan, said the calendar was the same each year. Biden agreed to that, but not to the underlying point, which was that it was a mistake for Obama to have announced a date for the withdrawal of the remainder of the U.S. combat troops.

On the nation’s economy, both men were asked directly when his side could reduce unemployment to 6 percent from the current 7.8 percent. Both men sidestepped.

Biden repeated the president’s contention that the nation is moving in the right direction, while Ryan stated the Republican view that economic struggle persists even though Democrats had control of both houses of Congress during the first two years of Obama’s term.

For Biden, Thursday night’s debate was his first since the 2008 campaign, when he shared a stage with Sarah Palin, then John McCain’s running mate.