Barack Obama’s record-breaking online fund-raising continued in March, netting $40m (£20m, €25m) from almost half a million donors in spite of his defeats to Hillary Clinton in Texas and Ohio at the start of the month.

Mrs Clinton’s campaign for the Democratic presidential nomination, which is estimated to have raised only half of Mr Obama’s total in March, on Thursday said that her opponent had been outspending her by four-to-one in Pennsylvania, which holds the next primary election on April 22.