The United States is in the grip of a migration crisis unlike it’s ever seen before. The seemingly never-ending flow of migrants into New York, Chicago and Denver has - according to those cities’ mayors - pushed their areas to breaking point.  The migrants themselves, bussed in from the border with Mexico, often end up in foreign cities without any assistance; injured, unwell and ill-prepared for freezing winter temperatures. And for president Joe Biden, these historic migration levels during an election year are a political nightmare. Today, digital foreign editor Chris Zappone on what impact this crisis could have on Biden’s election bid. And why it’s hampering his attempts to give aid to Ukraine.Subscribe to The Age & SMH: https://subscribe.smh.com.au/See omnystudio.com/listener for privacy information.