Mitt Romney and his Republican advisers claim momentum is on their side as the US presidential election enters the final stretch. Their unrelenting focus is on the ailing US economy and their claim that a Romney administration would rebuild America as a low tax, small government engine of economic enterprise. HARDtalk’s Stephen Sackur speaks to Grover Norquist, founder of the advocacy group Americans for Tax Reform - one of the most influential figures in Republican politics. Just how credible is the Romney rescue plan for America?