In this case, "suffering a new blow" is blow in the sense of an attack, a strike, a hit. A new blow means a new and additional setback to a cause. This is "suffered" by the person or entity damaged by the blow.
Example: "Gordon Brown's prospects of taking over at the IMF suffered another blow today as Business Secretary Vince Cable suggested the top job should go to someone from within the Eurozone."
In this example, the event described is another setback making former UK Prime Minister Gorden Brown's efforts to become head of the International Monetary Fund less likely to succeed. The context is continued vigorous opposition to Brown's candidacy by both coalition partners forming the sitting government of his own country. The more opposed the government becomes, the less likely Brown will succeed. Thus, another major cabinet minister opposing his candidacy is a new setback, i.e. a new blow.