Kamala Harris will step back into the political spotlight on Wednesday night to deliver a sharp critique of Donald Trump, warning that his presidency has put the US at risk of a constitutional crisis. The former vice-president has mostly kept a low profile since leaving the White House in January following her bitter defeat to Trump. Now, a day after Trump celebrated 100 days in office with a rally in Michigan, she is expected to deliver a forceful renunciation of the president’s stunning power grabs that have prompted warnings of creeping authoritarianism. In her remarks, Harris, 60, will warn of...