In his quest for a $210bn tax boost, President Barack Obama will look as far afield as the Cayman Islands and Amsterdam, but the toughest fight is back in Washington with the serried ranks of corporate and conservative America.

Anticipating reform, which was mooted by Mr Obama during his campaign for the White House, US multinational companies from Caterpillar to Pfizer are already engaged in fervent lobbying efforts to prevent more profits made in lower-cost jurisdictions being taxed at home.