Former US presidential candidate Mitt Romney has announced he is seeking a political comeback with an apparent dig at Donald Trump.

The 70-year-old Republican, who has been a vocal critic of the US president, will run for Utah's senate seat after keeping a relatively low-profile since losing to Barack Obama in 2012.

In a video on Twitter, Mr Romney said he hoped to bring "Utah's values" to Washington and touted his management of the 2002 Salt Lake City Winter Olympics.

In an apparent reference to Mr Trump's immigration policies, Mr Romney said: "Utah welcomes legal immigrants from around the world. Washington sends immigrants a message of exclusion.

"And on Utah's Capitol Hill, people treat each other with respect."


I am running for United States Senate to serve the people of Utah and bring Utah's values to Washington. pic.twitter.com/TDkas6gD2p — Mitt Romney (@MittRomney) February 16, 2018

Mr Romney is seeking to replace 83-year-old Republican Orrin Hatch, who is retiring despite being lobbied by Mr Trump to run for another six-year term.

Mr Trump has claimed Mr Hatch once told him he was "the greatest president in the history of our country".

Mr Romney, a wealthy businessman and former governor of Massachusetts, is the frontrunner to win the seat in the November elections.

He has previously called fellow Republican Mr Trump a "phoney" and a "fraud".

Image: Donald Trump and Mitt Romney had dinner in 2016 despite trading insults

"His promises are as worthless as a degree from Trump University," Mr Romney said.

"He's playing the members of the American public for suckers."

Meanwhile, Mr Trump has labelled Mr Romney a "failed candidate" who "choked like a dog" in the 2012 presidential race.

Despite the insults, the two men dined together in November 2016 after Mr Trump's election win while Mr Romney was in the running to be secretary of state before he was overlooked for the job.