Donald Trump has hit back at President Barack Obama for terming him unfit for presidency, saying the "terrible president" would go down as the worst in American history.
"Well he's a terrible president. He'll probably go down as the worst president in the history of our country, he's been a total disaster," Trump told Sinclair Broadcast group in an interview on Tuesday.
"You look at what happens in the Middle East, in Syria and his line in the sand. I think it just means he's concerned I'm going to win," he claimed.
"Don't forget last time he said I would never get the nomination, now he is saying I wouldn't get the election now all of a sudden he said the other day maybe I can win the election, no I guess he probably has to say that kind of thing," Trump said when asked about Obama's statement.
"I think the Republican nominee is unfit to serve as president. I said so last week and he keeps on proving it," Obama told reporters at a joint news conference with the Singapore prime minister on Tuesday.
Trump reiterated his stand and said he does not regret having criticised the parents of a slain Pakistani-origin American Muslim soldier Humayun Khan who was killed by a suicide bomber in Iraq in 2004.
"I don't regret anything. I said nice things about the son and I feel that very strongly but of course I was hit very hard from the stage and you know it's just one of those things but no I don't regret anything," he said.
Trump's own party leaders have come out openly against the Republican presidential nominee for being critical of family members of the soldier.
He also did not regret calling his Democratic rival Hillary Clinton as the devil.
"No, I don't think so; I think it is what it is. She's a very deceitful person, she lies, she cheats, no I don't think that's too far at all," he said.
He maintained his belief that the upcoming presidential election is rigged.
"I'm talking about at the voter booth. I mean we've seen a lot of things over the years and now without the voter ID's and all the things going on and some bad court cases have come down," Trump said.
"I just hear things and I just feel it and I felt it having to do with the primaries. I looked at Bernie sanders I said 'he isn’t going to win. I thought this whole thing was rigged and I think the general election is gonna be, we're gonna have a lot of problems we have to be very careful," Trump said.
During the interview Trump refused to entertain the challenge posed to him by Warren Buffet on revealing his tax returns, saying he does not know Warren Buffet and has never met him.
Meanwhile, Trump has pitched for good relationships with China and Russia, stating that it would be nice for the US to get along with the two nations, as he slammed Hillary Clinton for having bad relationship with Vladimir Putin.
"As far as I'm concerned, I want to get along with China. Wouldn't it be great if we got along with Russia? Wouldn't that be great?" Trump said at an election rally in Ashburn, Virginia, a suburb of WashingtonDC on Tuesday.
Seeing a potential partner in Russia in wiping out the Islamic State terror group, Trump said, "If we actually had a relationship with Russia, instead of all the fighting and the problems, we could get Russia and others to partner up against ISIS."
Having not seen any good done by the existing set of experts in the current global situation, Trump said he won't take advice from anyone.
"Hillary Clinton will be worse. She has bad relationships with people like Putin. I'll give you an example. She has terrible relationships with Putin. This is a nuclear country we're talking about. Russia, strong nuclear country," he said.
He further said that he wants tough people and Clinton is not tough.
"I know tough people, she's not tough. I mean she's doing the handlers, they push her from place to place that's all it is."
"She wants to play the role of the tough guy against Putin She should be tough on trade. Because right now we are being ripped off on trade like nobody has ever ripped us off in history. You look at our trade deficits with China," he said.
On Barack Obama supporting Clinton for the Presidential race, Trump reminded people of the things Obama said about Clinton said years ago.
"Eight years ago Barack Obama said things about her that were so bad, and today I just said, do me a favor look them up because I remember how bad. Now all of a sudden he's supporting her," he said.
The 70-year-old White House hopeful warned the people about Clinton's plans to keep Obamacare, which he said will lead to "people pouring into our country".
"Look it's a hope, because she's going to keep Obamacare, She's going to let the Syrian refugees come in and we don't know if they're ISIS, we have no idea," he said.