The tempo of a townhall-style debate can be hard to control,
because you never know what will be on the voters' minds. McCain
usually does well in this format, but occasionally has off days and
doesn't do well with the economic subject matter that is likely to
dominate.
All Obama has to do is be likable, competent, and
non-condescending. McCain has the tougher challenge because he's
behind. If he wants to do well, he could do worse than listening to
Bill McGurn: hammer away at tax
increases, run against the unpopular Democratic Congress, and
remind voters what happened the last time a Democratic presidential
candidate promised a middle-class tax cut. But he'll have to be
careful: a lot of those voters wouldn't mind having the 1990s
economy, which is Obama's obvious retort.