Vice President Kamala Harris hasn’t held a formal press conference with reporters since she became the presumptive and now official Democratic nominee.

Dig a little deeper, though, and there are signs that it would be premature for Ms Harris’ team to become complacent. National polls may offer a promising outlook, but do not reflect how, or where, the White House will be won.

Kamala Harris has suffered a new blow to her election campaign after one of America's most powerful unions ruled out endorsing a presidential candidate for the first time in 30 years.