Transcript for Michael Bloomberg on his possible 2020 presidential run

money where your mouth is? Michael Bloomberg put $100 million behind candidates in the midterm election which helped turn the tide blue. He's also taking on the white house's environmental policy in his new documentary, "Paris to Pittsburgh." Please welcome a man who would have my vote in 2020, just saying, Michael Bloomberg. Michael, Mr. Mayor -- I'll call you Mr. Mayor. You always keep those titles, don't you guys? You spent over $100 million helping Democrats in the midterms, in 21 of 24 people that you backed won. I think 15 were women. And all of them care very much about -- 18 were women and, the blue wave, yeah. Care about climate change and want background checks for guns, not to eliminate guns but want background checks. So you got everything you were hoping for. Okay, so what are you hoping that all that money gets you in January when they take over? What's going to happen then? Good government. I've said this a number of times, the Republicans did not exercise the check and balance on the white house that the constitution calls for, and they were unwilling to take on any of the controversial issues, any of the major things facing this country. They did absolutely nothing. Time for a change. In business you would fire somebody if they did a terrible job. We just fired a bunch of people. Why do you think the GOP was so reticent? They became a party rather than a personality and I think they're going to pay for it because when Mr. Trump is not popular, it hurts them at the ballot box and they're going to really suffer. You've been very critical of president trump and you've been openly weighing a run against him in 2020. Do you regret that you didn't run the last time? No. I think we found that you cannot win as an independent because the electoral college requires a majority, not a plurality. Even if I did get a lot of electoral votes, you couldn't possibly win it. It would have gone to the house and the house would then pick the Republican candidate or next time pick the democratic candidate. And you have to have -- You become a spoiler in a way. That's exactly what my obit would have been, he was a spoiler. This way they can write other things about me when I pass. What would make it more appealing to you then for 2020? Well, you would only run if you could get the Republican or the democratic nomination. Obviously the Republican is probably not going to be available and I don't agree with almost everything they stand for today. So it would have to be the democratic nomination. If you want to run that's what you would have to do and I don't know. I've looked at it and I've said at the beginning of the year we'll focus on it. You would be running as a Democrat, correct? No, you would have to run as a Democrat and before I forget, I just want to say, your father was one of my heros. It's a little strange interviewing you. We've been long-time family friends. I was going to say, I knew you when you were this tall. I know. You're a true friend to my family. Weren't you a pallbearer? Yeah. Pallbearer at the funeral. Pallbearer and her father campaigned for me on the streets in Brooklyn back in 2000. One of the most memorable moments of my childhood is going to an Italian dinner downtown with you and your wonderful girlfriend. It's weird to be interviewing you. Where do you fit in the democratic party? Obviously you won as a Republican, as an independent, but the excitement right now seems to be behind the more extreme wing of the democratic party, Bernie Sanders, Alexandria ocasio-cortez. You would actually probably be more with trump on things like China and maybe some business dealings I would imagine. I think for example on China, it is asymmetrical. It's not fair to us. We should do something about it. So you agree with him there? With what he's trying to do but not the way -- you don't do it by going and pushing the other person into a situation where they can't possibly give you what you need. Negotiations don't work that way. You want to walk away with both sides thinking they got something and we should push China. I'm the first one to advocate for doing it but it's the style that you do it -- What happened to the art of the deal? I thought that's his whole thing. Well, that's the name of the book. A bit of diplomacy. You think though you can get through the democratic primary as it exists today? That's exactly what you have to try to figure out. I think most Democrats want a middle of the road strategy. They want to make progress, but they're not willing to go and to push something that has no chance of ever getting done and wasting all their energy on that. We have things that we need done. We have to create jobs for people today. We have to find a way to get medical care for people today. We have to fix our education system, immigration, climate change, guns. There's no lack of issues you have to face. If you go off on trying to push for something that has no chance of getting done, that we couldn't possibly pay for, that just takes away from where you can really make progress and helping people that need help today. It will be interesting to see how that plays out. You've made a lot of calls for bipartisanship but you're a leading voice in the anti-gun movement which puts you immediately at odds with a lot of Republicans. You spent a lot of money but congress hasn't taken up any major gun control pressures at the national level since sandy hook, so do you feel like your efforts have been effective? What I have asked for and most of my friends have asked for are background checks. We shouldn't be selling guns to minors, to people with psychiatric problems, or people with criminal records. Other than that, the second amendment gives you the right to own weapons and there's nothing wrong with that. It's the constitution. We're not going to change it. I think automatic weapons don't make a lot of sense but if you want to buy a gun and go through the background check process, that's what the law lets you do. I'm not opposed -- I'm not in favor of taking that away one bit. In fact, an NRA member came up to me yesterday and said I disagree with you on guns but I and all my friends are going to vote for you. I think there are restrictions you can put on it, who you sell guns to. Does it disharten you that there hasn't been any legislation passed? Yes. But not taking away guns. You have to go through the background check process. 19 states have voted for it but the government has not implemented it and there are another 31 states we can get at the local level. It would be easier if congress did it. Just have background checks. When you survey NRA members, 80% want background checks.

This transcript has been automatically generated and may not be 100% accurate.