MEXICO CITY • There is a debate under way within the Democratic Party over what kind of candidate can beat US President Donald Trump in 2020. A centrist candidate will attract moderate Republican voters, but perhaps demobilise young, minority, college-educated Democrats. A more exciting, perhaps more radical candidate, will mobilise Democrats but scare away moderate Republicans.

From the perspective of a citizen of the country that has probably suffered most under the Trump administration's policies, the debate signals a historic shift.