The former White House press secretary, who left the job in 2019 to return to her home state, launched the bid less than a week after the end of Trump's time in office and as the former US president faces an impeachment trial.

But her announcement reflected how much she expected voters in solidly red Arkansas to embrace the ex-president.

"With the radical left now in control of Washington, your governor is your last line of defence," Sanders said in a video announcing her bid.

"In fact, your governor must be on the front line. So today I announce my candidacy for governor of Arkansas."

The daughter of former Governor Mike Huckabee, Sanders had been widely expected to run for the office after leaving the White House - and Trump publicly encouraged her to make a go.

She's been laying the groundwork for a candidacy, speaking to Republican groups around the state.

Sanders joins a Republican primary that already includes two statewide elected leaders, Lieutenant Governor Tim Griffin and Attorney General Leslie Rutledge.

The three are running to succeed current Governor Asa Hutchinson, a Republican who is unable to run next year due to term limits.

No Democrats have announced a bid to run for the seat.

Sanders was the first working mother and only the third woman to serve as White House press secretary.

But she also faced questions about her credibility during her time as Trump's chief spokeswoman.

During her nearly two-year tenure, daily televised briefings led by the press secretary ended after Sanders repeatedly sparred with reporters who aggressively questioned her about administration policy and the investigation into claims of coordination between Trump's campaign and the Russian government.

But Sanders earned reporters' respect working behind the scenes to develop relationships with the media.

Sanders, who published a book titled Speaking for Myself last year and joined Fox News as a contributor after leaving the White House, enters the race with a much higher profile than any of the candidates.

She remains an unknown on many of the state's biggest issues, though in her announcement she called for reducing state income taxes and cutting off funding for cities that violate immigration laws.

Australian Associated Press