Joe Biden down played his age at Tuesday's Democratic debate as he baffled viewers with a series of gaffes as he tried to explain his tax policy, attack Donald Trump's foreign policy, and caught himself before he claimed he ended Roe vs. Wade, the landmark case that legalized abortion in America.

Biden, who's struggled to overcome a damaging narrative about his age after a series of mistakes on the campaign trail, left the audience with several head scratching moments in the second Democratic debate.

The former vice president, during an attack on his rivals Elizabeth Warren and Bernie Sanders, stopped himself just in time from making a claim about ending abortion in America.

'Senator Warren said we can't be running any vague campaigns. We've got to level with people. We've got to level with people and tell them exactly what we're going to do, how we're going to get it done, and if you can get it done. I'm going to say something that is probably going to offend some people here, but I'm the only one on this stage that has gotten anything really big done from the Violence Against Women Act to making sure that we pass the Affordable Care Act to being in a position where we, in fact, took almost a $90 billion act that kept us from going into a depression, making us -- putting us in a position where I was able to end Roe -- excuse me,' he said, stopping abruptly.

Bernie Sanders, Joe Biden and Elizabeth Warren were asked about their age at Tuesday's debate

Joe Biden, 76, said he would release his medical records before voters go to the polls

CNN's Anderson Cooper, one of the debate moderators, asked Biden who was being vague.

Biden struggled to answer as he attacked Warren and Sanders, particularly their universal health care plan.

'Well, the senator said - she's being vague on the issue of - actually both are being vague on the issue of the Medicare for All. Look, here's the deal. Come on. It costs $30 trillion. Guess what? That's over $3 trillion -- it's -- let me finish. If you eliminate the entire Pentagon, every single thing, plane, ship, troop, the buildings, everything, satellites, it would get you -- it would pay for a total of four months. Four months. Where do you get the rest? Where does it come from?,' he said.

Biden, at 76, would 79 years old on inauguration day if he wins the 2020 presidential election.

At the debate, CNN's Erin Burnett asked him about his age, which the former vice president argued was a boon to his campaign as it gave him experience.

'If you're elected, you will turn 80 during your first term. Last month former president Jimmy Carter said he could not have undertaken the duties of the presidency at 80 years old. Why are you so sure that you can?,' Burnett said.

'Because I watched it. I know what the job is. I've been engaged. Look, one of the reasons I'm running is because of my age and my experience. With it comes wisdom,' Biden said.

'We need someone to take office this time around who on day one can stand on the world stage, command the respect of world leaders from Putin to our allies, and know exactly what has to be done to get this country back on track. It is required now more than any time in any of our lifetimes to have someone who has that capacity on day one. That's one of the reasons why I decided to run, why I decided to run this time, because of I know what has to be done,' he added.

He also vowed to release his medical records although he would not give an exact date as to when.

'I know what has to be done. I will not need any on the job training the day I take office. And I will release my medical records, as I have 21 years of my tax records, which no one else on this stage has done, so that you can have full transparency as to my health and what I am doing,' Biden said.

He said the medical records would come 'before the first vote.'

The Iowa caucuses - the first vote in the Democratic primary process - takes place on February 3, 2020.

'Before Iowa. I mean, look, I've released them before. I released 55 pages of my - I'm the only guy that's released anything up here,' he said of his Democratic rivals.

Bernie Sanders reassured viewers he was healthy after his heart surgery

Elizabeth Warren said she can outwork any Republican

Bernie Sanders, 78, and Elizabeth Warren, 70, - also among the oldest candidates in the Democratic field - were asked about their age.

Sanders, who had a stint put in his heart a few weeks ago, reassured viewers he was back and healthy.

'We are going to be mounting a vigorous campaign all over this country. That is how I think I can reassure the American people. But let me take this moment if I might to thank so many people from all over this country, including many of my colleagues up here, for their love, for their prayers, for their well wishes. And I just want to thank you from the bottom of my heart, and I'm so happy to be back here with you this evening,' he said.

And Warren said she could outwork any Republican.

'Well, I say I will outwork, out-organize, and outlast anyone, and that includes Donald Trump, Mike Pence, or whoever the Republicans get stuck with,' she said.

The age questions followed a series of mix-ups by Biden, who struggled to explain his tax plan, confusing whether he was going to eliminate or increase a tax on capital gain.

He also mixed up Iraq and Afghanistan when talking about foreign policy - notable moments for the former vice president who made a series of gaffes on the campaign trail when talking about his work in the political arena and struggled with mistakes in earlier Democratic debates.

During Tuesday's three-hour debate in Ohio, Biden struggled to explain his own tax plan.

'I would eliminate the capital gains tax - I would raise the capital gains tax to the highest rate, of 39.5 percent. I would double it, because guess what? Why in God's name should someone who's clipping coupons in the stock market make -- in fact, pay a lower tax rate than someone who, in fact, is -- like I said -- the -- a schoolteacher and a firefighter? It's ridiculous. And they pay a lower tax,' he said when asked about Sanders' and Warren's plans to raise taxes on the wealthy.

Joe Biden struggled to explain his tax plan at Democratic primary debate, mixing up if he would eliminate or increase a capital gains tax

'You can't justify $600 billion of that. We could eliminate it all. I could go into detail had I the time. Secondly -- thirdly, what we need to do is make it clear to the American people that we are going to -- we are going to raise taxes on the wealthy. We will reduce tax burdens on those who are not. This is one of the reasons why these debates are crazy. Because everybody tries to squeeze everything into every answer the fact is everybody is right about the fact that the fourth industrial revolution is costing jobs, it is,' Biden added.

Capital gains are profits made on the sale of stocks, bonds, precious metals, real estate, and property.

In the United States, the tax rate on long-term capital gains is lower than the ordinary income tax rate, and in some tax brackets there is no tax due on such gains - which usually benefits the wealthy.

Biden, the former head of the Senate Foreign Relations Committee, also mixed up Iraq and Afghanistan when talking about President Donald Trump's foreign policy and after he had to hug it out with Bernie Sanders over a perceived insult.

'We have an erratic, crazy president who knows not a damn thing about foreign policy and operates out of fear for his own reelection,' he said, following up on an answer Sanders gave about Russian President Vladimir Putin.

'Think what's happened. The fact of the matter is you have Russia influencing and trying to break up NATO. What does the president do? He says I believe Vladimir Putin. I believe Vladimir Putin, I don't believe our intelligence community,' Biden noted.

Sanders stepped in: 'You're suggesting I'm Vladimir Putin here.'

'No, I'm not,' Biden responded and gave the senator a hug.

He then returned to his criticism of Trump and made another gaffe.

'What is happening in Iraq - excuse me, in Afghanistan - as well as all the way over to Syria, we have ISIS that's going to come here. They are going to in fact damage the United States of America. That's why we got involved in the first place,' Biden said.

In the first president debate Biden struggled to respond to an attack from Senator Kamala Harris on his opposition to a federal school busing programs in the 1970s.

In the second debate, he messed up his closing statement when he gave out a number - Joe30330 - but forgot to tell viewers they are supposed to text to it although he later joked media attention to the gaffe brought his campaign the attention he had wanted it to get.

Biden's word salad moments Tuesday night were a stand out one in the crowded field of 12 candidates on the Democratic stage as he struggled for air time on the busy stage.

Elizabeth Warren, who has jumped ahead of Biden in recent polls on the Democratic nomination, was leading in talk time, according to a count by debate sponsor CNN.

Joe Biden and Bernie Sanders had a hug it out moment during the debate

Warren had nearly 11 minutes in air time before the first commercial debate while Biden was in third place with just over 5 minutes.

Biden's other stand out moment was his fierce defense of his son Hunter’s work with a Ukrainian gas company when he was vice president.

‘My son did nothing wrong. I did nothing wrong. I carried out the policy of the United States in rooting out corruption in Ukraine,’ he said.

The former vice president argued the focus should be on President Trump.

‘This president on three occasions, three occasions has invited foreign governments and heads of government to get engaged in trying to alter our elections. The fact is that it is outrageous. Rudy Giuliani, the president and his thugs have already proven that they, in fact, are flat lying. What we have to do now is focus on Donald Trump. He doesn't want me to be the candidate. He is going after me because he knows if I get the nomination, I will beat him like a drum,’ he said.