Brexit is the main mess he'd have to address, and he would do it with the dignity needed to get a genuinely mutually beneficial outcome.
He's characterially unprovocative, temperate in his arguments, and eminently reasonable.

He will not pull the bad faith capers the UK is so notorious in Europe for, and would help create a fairer, more equitable unity, supposing anyone there will listen.
He's humble without being ingratiating, calm but firm, a steady hand on the tiller.
Meanwhile the Tories are running out of dirty tricks they can use under the radar, (now this FB scam is exposed). Thanks to social media hot-wiring public opinion with increasing effect, the young are especially drawn to his chilled vibe. Concerned, tenacious and grounded is how he comes across, but above all genuine.

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty