There is a right way and a wrong way to blame George Bush for future budget deficits. The wrong way is to get mad about his tax cuts and the Iraq war. By 2019--the end of the budget window, and the period with which us structural deficit hawks are concerned--the Bush tax cuts will have long since expired. We are also scheduled to have withdrawn from Iraq. You cannot explain any portion of the 2019 budget deficit with these two factors.
Better is to point to the increase in net interest on the debt under Bush, which is, indisputably his fault. (Well--him and the Republican Congress.) That's about $100 billion a year, although since Bush shrank the average maturity of US debt from 60-70 months down to 48, if our unusually low interest-rate environment persists much longer, we'll have refinanced most of that debt at very attractive rates. Call it $75-90 billion, anyway.
The other major contribution that Bush made was the atrocious Medicare Part D, which sucks about 75% of its revenue from the general fund. This is a hard criticism for Democrats to mount, since they wanted the damn thing to be even bigger, but luckily I hated it from the beginning, and am thus bound by no such qualms. By 2018, Medicare Part D will, barring legislative change, rake $100 billion off the annual budget.