US rapper Kanye West has said he is running for president, potentially pitting him against a man he says he admires, Donald Trump.

"We must now realize the promise of America by trusting God, unifying our vision and building our future," he tweeted. "I am running for president of the United States!"

His wife Kim Kardashian West and entrepreneur Elon Musk endorsed him.

But it's unclear whether West is really running.

He does not appear to have registered his name with the Federal Election Commission (FEC) for November's election. The closest name the FEC database shows is a candidate called "Kanye Deez Nutz West", who filed their papers with the Green Party in 2015 under the address "1977 Golddigger Avenue, Suite Yeezus" and appears to have raised no money.

It is also not the first time West has claimed that he is running for the White House.

At the 2015 MTV Video Music Awards, he said he had decided to run for president in 2020.

But last November he pushed the date back, saying he would actually run in the 2024 contest.

"What are you laughing at?" he asked the crowd at Fast Company's Innovation Festival.

"We would have created so many jobs that I'm not gonna run, I'm gonna walk," he said, adding he was considering changing his name for the run to "Christian Genius Billionaire Kanye West".

In his tweet on Saturday, US Independence Day, West, 43, did not say if his supposed run would be affiliated with a particular political party.

In any case, contesting the nomination of one major parties would be impossible at this stage, with the election only four months away.

In order to appear on the ballot as an independent candidate, West would have to gather a certain amount of signatures and register in states by a particular deadline. The deadline has already passed in some major states but the music star would still technically have time to file in many others.

This year's contest is likely to be a straight battle between Republican President Donald Trump and Democrat Joe Biden.

In 2018, West made a bizarre appearance at the White House with President Trump during which he wore a Make America Great Again hat and made an expletive-filled rant that Mr Trump described as "quite something".

"I love this guy right here," West said, walking behind the desk to hug the seated president, who said: "That's really nice."

The rapper also pushed back on the idea that African-Americans are overwhelmingly Democratic Party voters, saying: "People expect that if you're black, you have to be Democrat."

Kim Kardashian West retweeted her husband's statement about the presidential run with an American flag.

She has in recent years become a significant voice in the US movement for criminal justice reform and has successfully lobbied President Trump to release several prisoners.