In the tweet, he explains that in recent weeks he has been torn between loyalty to his family and the nation's best.
"It's an insoluble tension and it's time for someone else to take up my role in Parliament," he concludes his tweet.Elected since 2010
Jo Johnson has been elected since 2010 and has a much more positive view of the EU than his brother. It is hard to believe that he shares the Prime Minister's view that it is possible to leave Europe without a deal - a "no-deal Brexit". That's what The Guardian writes.
It is not clear if Jo Johnson is leaving his post immediately or if it is an indication of whether he will stand as a candidate in the next parliamentary election.