Hillary Clinton's search for a vice-president started with a commanding victory in the New York primary and a special delivery in a plastic Duane Reade bag. Three months later, it ended with a phone call to a shipyard office, where Virginia Senator Tim Kaine was waiting.

From the start, Kaine was a front-runner to join Clinton on the Democratic ticket. A senator, former Virginia governor and mayor of Richmond, he hails from a top battleground state and, as a fluent Spanish speaker, could help in another: Florida. Victories in both would likely put the White House out of the reach of Donald Trump and his running mate, Indiana Governor Mike Pence.

But Clinton grew personally comfortable with the likable and even-keeled Kaine as they campaigned together in recent weeks and discussed the vice presidency. Clinton ultimately concluded that she had "unshakeable confidence in Kaine's readiness to do the job", according to a Clinton aide familiar with her thinking. The aide spoke on condition of anonymity to describe the private deliberations over her selection.