A bail bondsman charged alongside former US president Donald Trump and 17 others in the Georgia election interference case has become the first defendant in the case to accept a plea deal with prosecutors. 

Under the deal in which Scott Graham Hall pleaded guilty, he will receive five years of probation and he agreed to testify in further proceedings.

He was also ordered to write a letter of apology to the citizens of Georgia and forbidden from participating in polling activities.

The 59-year-old pleaded guilty to five counts of conspiracy to commit intentional interference with performance of election duties, all misdemeanours, at a surprise court hearing.

Prosecutors had accused him of participating in a breach of election equipment in rural Coffee County and initially charged him with racketeering and six conspiracy counts, all felonies.

Hall is one of the lower-level players in the indictment filed last month alleging a wideranging scheme to overturn Democrat Joe Biden's presidential victory and keep Mr Trump, a Republican, in power.

But the plea deal is a major development in the case and marks a win for Fulton County District Attorney Fani Willis as she pursues a historic racketeering case against a former president.

Hall's attorney Jeff Weiner, who was in court with him on Friday, said under the deal, his client's record would be wiped clean after he completed probation.

The agreement allows Hall to avoid the stress of "living under a serious felony indictment" without knowing when he might go to trial, the attorney said in a phone interview.

"This way, it's over," Mr Weiner said.

"He can sleep well and get on with his life."

Mr Weiner said Hall did not know much about the alleged conspiracy, and he would be surprised if prosecutors called him to testify.