Watch: Indian-origin schoolgirl stumps British PM David Cameron with her question

London: It was not any of the hard-nosed journalists or politicians but a 10-year-old Indian-origin schoolgirl that has stumped the British Prime Minister on the campaign trail.

Reema, a student from the northern England city of Salford in Greater Manchester, asked a question regarding his favourite politician apart from himself in BBC's children's programme 'Newsround' as part of a series on the upcoming General Election on May 7.

"If you could pick one politician apart from yourself to win who would it be and why?," 10-year-old asked Cameron.

48-year-old Prime Minister looked visibly rattled and failed to come up with an answer.

"Wow. If I could pick a politician? Would they have to be living or dead?"

"If I thought someone else should win the election I would not be standing myself, so I can't really answer the question about who else I would like to win," he said.

"There are lots of candidates around the country I am very enthusiastic about."

"I am afraid it is too difficult to say I would like someone else to win other than me or I wouldn't be here, and I am quite keen on winning," he added.

"Top question, it is the best one I have been asked all election campaign," Cameron said when he was leaving.

Cameron answered other questions on topics such as immigration, what it's like to be Prime Minister, and how much it now costs to go to university.

He was also quizzed on the noisy behaviour of MPs in the British Parliament.

'Newsround' is interviewing leaders from all major parties in the lead up to next month's polls.

Watch: The moment when David Cameron was left stumped by 10-year-old girl's question.