A group of Roman Catholic Nuns that have been travelling across the US in a bus, have been preaching a message of social justice and campaigning against spending cuts for the poor. Arriving at their final destination, Washington DC, they have targetting mostly Republican members of Congress who are in favour of deep cuts in social programs to balance the debt-laden US budget. But the drive has been accused of being too politically partisan and has also raised the ire of the Vatican. Al Jazeera's John Terrett explains.