Kaine will help her present a steady alternative to the unpredictable campaign of the Republican billionaire businessman.

Clinton – who will be formally nominated as presidential candidate at the upcoming Democratic convention – announced her running mate on social media.

“I’m a very strong supporter of Secretary Clinton and I live in a state that I think is going to be one of the three or four most critical states in the presidential election,” Kaine said on Thursday, ahead of the announcement.

“So I have got a lot of really good work to do here on the campaign trail for her as a Senator and I’m just, you know, the waiting game is almost over.”

Kaine, a self-described “boring” Virginian, could appeal to independents and moderates. But liberals are dismayed that he has been chosen – they object to his advocacy for an Asian free-trade pact.

Clinton has been leading Trump in many opinion polls, but there is still more than three months to go until the much talked about election. (Euronews)