The Mayor of South Yorkshire, Dan Jarvis, has announced he will step down from the role next year.
Mr Jarvis, who is also the Labour MP for Barnsley Central, said it had been an "extraordinary privilege" but he would not seek re-election in May 2022.
He was elected as the first South Yorkshire Mayor in 2018.
Mr Jarvis said he wanted to announce his intention to stand down in order to allow potential candidates "sufficient notice to step forward".
The former soldier said: "We now need someone to build on our achievements and drive us forward over the next four years.
"[But] that person will not be me. I won't be standing as Mayor again next May, but in the meantime I will continue to give 110% to the role."
The Labour leader Sir Keir Starmer tweeted Mr Jarvis had achieved a great deal as mayor and thanked him for all he had done in the role.
"He's shown what can be done when Labour is in power, putting Labour values into action. I'm pleased that he'll continue as an MP - representing and championing the people of Barnsley," he added.
Liz Roberts, BBC Radio Sheffield political reporter
When Dan Jarvis was first elected, it's fair to say that most people didn't really know what they were voting for.
There was no devolution deal, no money and no power.
The new mayor spent more than two years getting that job done. It required a lot of diplomacy, both with the opposition government and with fellow Labour council leaders across South Yorkshire.
It was also a job he took no salary for, and it's currently given to local good causes.
He would always have to make a choice though, which job did he want more? Unlike other Labour MPs who've chosen to leave Westminster for regional roles, Dan Jarvis has decided to stay in Parliament.
In the past he's been tipped as a potential party leader, so he may have his sights set on other political ambitions.
When Mr Jarvis was first elected as mayor he had no additional powers or money as the devolution deal had not been agreed due to continued arguments about a Yorkshire-wide deal.
However, the government would reject that idea and South Yorkshire's arrangements were formally approved by Parliament in 2020.
It gave the mayor and combined authority power over transport, strategic planning and skills in the region, plus £900m over 30 years.
The South Yorkshire mayor powers do not include the Police and Crime Commissioner role, unlike West Yorkshire's mayor, which meant Mr Jarvis was able to continue as an MP.
"Some people didn't agree with that, but I said from the beginning that this wasn't a long-term arrangement. And I meant it," Mr Jarvis said.
Reacting to his decision, the Labour MP for Sheffield Heeley, Louise Haigh, tweeted her thanks for all he had done to bring money and powers to South Yorkshire.
"I look forward to continuing to work alongside him in Parliament to drive investment for South Yorkshire," she added.