Mrs May, the Prime Minister and Tory leader, was in Birmingham to back Mr Street and to attend the UK-Qatar Business and Investment Forum at Birmingham’s ICC, the day before she triggers Article 50 and begins the process of taking the UK out of the European Union.
Other candidates standing for the post of West Midlands mayor include Labour candidate Sion Simon.
Speaking to the Birmingham Mail, Mrs May said: “I think it’s important for the West Midlands that they have as mayor somebody that can deliver for them.
“This is about bringing the West Midlands together and ensuring we are getting that economic growth, that prosperity, is going to help people in all parts of the West Midlands.
“The other reason I think it’s so important is because this is an opportunity for people to vote for a different sort fo candidate.
“Andy is not an ex-politician. He is somebody who has a completely different background.
“And that’s particularly relevant because of the mayoral role.
“Andy has headed up a company employing 30,000 people. He knows about creating jobs.
“So I think he’s got a track record of delivery but as I said I think he’s a different sort of candidate.”