The day before Elizabeth Warren announced she was leaving Harvard to run for the US Senate, she gave Deval Patrick a call to ask for advice, eager to hear what a novice campaigner could learn from a veteran. Now, as the former Massachusetts governor and the Bay State's senior senator both seem to be positioning themselves for 2020 presidential runs - perhaps against each other - they could soon both need plenty of water as they shout themselves hoarse at campaign stop after stop, trying to stand apart from the pack - and each other.