Washington, Oct 17 (IANS): US President Donald Trump has jokingly encouraged his former presidential rival Hillary Clinton to run against him in 2020, saying that she lost to him last year partly because "she wasnt good at what she did".

"Oh, I hope Hillary runs. Is she going to run? I hope. Hillary, please run again!" Trump said during a Rose Garden news conference with Senate Majority Leader Mitch McConnell on Monday.

Trump broke through the so-called "blue wall" in a surprise electoral victory in November last year, winning states such as Michigan, Pennsylvania and Wisconsin. 

Clinton won the national popular vote by nearly 3 million votes but Trump tried to cast doubt on that achievement, citing widespread voter fraud without presenting evidence to back up such a claim.

Earlier on Monday, Trump had returned to his mocking nickname for Clinton, writing in a morning Twitter message that he "was recently asked if Crooked Hillary Clinton is going to run in 2020? My answer was, 'I hope so!'"

The President was asked about comments from the former Democratic presidential nominee defending the right of National Football League (NFL) players to kneel during the national anthem. 

"She's wrong... That's why she lost the election," Trump was quoted as saying by the Washington Post.

Clinton said on Sunday that Trump's attack on the NFL players is one of the "very clear dog-whistles" the President sends to his political base, Fox News reported. 

Most of the protesting players are black and Trump's core political supporters are overwhelmingly white, the report said.

"Actually, kneeling is a reverent position," Clinton said in London, where she was promoting her book about the 2016 campaign. "It was to demonstrate in a peaceful way against racism and injustice in our criminal system."

At the news conference, Trump said that anyone kneeling during the playing of the national anthem at sporting events is "sitting, essentially".

"You're disrespecting our flag, and you're disrespecting our country," he said.

The NFL should have suspended some players for multiple instances of kneeling, Trump said.

"But if Hillary Clinton actually made the statement that a form of sitting down during the playing of our great national anthem is not disrespecting, then I fully understand why she didn't win," he said.

"Look, there are a lot of reasons she didn't win, including that she wasn't good at what she did."