McCain needs Hillary to run because that's what keeps the Republican coalition together. She helps unite the Republican base.
With the likely nominations of Barack Obama by the Democrats and John McCain by the Republicans, one of these two parties is headed for a 2009 crack-up that could prove as messy as any party civil war in recent history.
The more there is scandal and corruption in Washington, the better it is for McCain, so he`s at a high point right now.
Presidents seem to fall into two positive categories: they're one of us, or they're heroes. Both McCain and Obama probably see themselves as potential heroes - presidents who will be looked up to, not presidents everyday people will remark are 'just like me.'