John McCain and Barack Obama on Monday kick off the first formal week of the general election race, signalling they plan over the next 58 days to fight an unexpectedly conventional battle for swing voters in a handful of states in which attacks on personality will play a big role.

Mr McCain, whose selection last month of Sarah Palin, the governor of Alaska, as his running mate enthused his Republican party’s conservative base, on Sunday made it clear he intends to campaign as a bipartisan “maverick” who will change Washington.