Just Jeb! Bush vows to be different to brother George as he unveils 2016 campaign logo

John Ellis Bush, or just "Jeb!" as his new campaign slogan declares, was poised to launch his bid for the White House in Miami overnight - with an identity crisis to deal with.

Listen to rivals on the right, and voters might be forgiven for thinking this is George W Bush's softer, gentler brother: tolerant on immigration, interventionist on education and edging away from the family record on foreign policy.

Back in his home state, the former Florida governor is expected to emphasise a very different side to his character, focusing on his record as a godfather of fiscal conservatism who took on public sector unions and blocked so many spending bills he became known as "Veto Corleone".

"When people tell me he's too moderate, I laugh at them," said Van Poole, a former Republican state party chairman and Tallahassee lobbyist now helping raise funds for the Jeb campaign.

"All you have to do is look at what he did when he came in [as governor]."

Like his brother's "compassionate conservative" campaign in 2004, supporters argue this passion for small government is tempered by a belief that it can be a more effective way of helping the less fortunate in society.