Former South Carolina Mark Sanford has become the latest Republican to challenge President Donald Trump in the GOP’s primary contest.

Mark Sanford, a long-time Trump critic, said in an interview announcing his candidacy: “I’m here to tell you now that I am going to get in.”

The former governor is the third person to challenge Donald Trump for the nomination.

However, it is seen as near impossible that anyone will take the Republican mantle from the president. No sitting president in the modern era has lost the race to be nominee for their own party, and Donald Trump remains very popular with Republicans.

The Republican National Convention, at which the nominee will be formally chosen, will take place in late August 2020 after a series of state primary elections and party caucuses.

However, some state Republican parties, including in South Carolina, have decided not to hold primaries in 2020 – to clear the path for Donald Trump and save money.

Mark Sanford, 59, is expected to centre his campaign on cutting government debt and spending.

He told Fox News on September 8: “I think we need to have a conversation on what it means to be a Republican. I think that as a Republican party we have lost our way.

“We have lost our way on debts and deficits and spending… The president has called himself the king of debt, has a familiarity and comfort level with debt that I think is ultimately leading us in the wrong direction.”

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In April, former Massachusetts Governor Bill Weld became the first person to challenge Donald Trump.

Bill Weld was followed by conservative radio host and former lawmaker Joe Walsh at the end of August.

Mark Sanford first served in Congress in 1995, representing South Carolina’s first congressional district. He later served as the state’s governor for two terms from 2003-2011. He then returned to the House in 2013.

The former governor criticized Donald Trump during the 2016 presidential election but ultimately supported him. However, Mark Sanford would become one of his toughest Republican critics in Congress when President Trump took office.

That stance cost Mark Sanford the Republican primary when his seat was up for re-election last year. He was beaten by a pro-Trump challenger who went on to lose the election to her Democrat opponent.

Mark Sanford is known as a fiscal conservative and has been attacked by President Trump over an extra-marital affair that tainted his second term as governor.

He went missing for several days, with his staff telling reporters he had gone to hike the Appalachian Trail.

Mark Sanford later admitted he had instead gone to Argentina to see his mistress.

Election Day is still more than a year away but the race to become the Democratic challenger to President Trump is already well under way.

Bernie Sanders and Joe Biden have thrown their hats into the ring, but most of the other candidates are relatively unknown outside the Washington DC bubble.