Democrats face close battle in key primaries as Obama tries to repair damage by pastor

Barack Obama, facing increasingly close primary contests today in Indiana and North Carolina, fought off a populist push by Hillary Clinton to capitalise on American unease at rising petrol prices.

Under pressure to prove his electability following the uproar over his outspoken Chicago pastor, Obama was yesterday forced on the defensive for a second time - over his opposition to Clinton's proposal for a summer petrol tax respite.

As the candidates divided the final hours before today's vote campaigning between the two states, Clinton released television ads accusing Obama of failing to understand the economic hardships of ordinary voters because of his opposition to her proposal for a summer respite on federal petrol tax.