The bushies would like to blame the economy. There are some other opininions though. For instance, a detailed analysis by The Angry Bear (via Thinking it Through) suggests:

Of the 80% of the deficit not related to terrorism, roughly 1/3 of the blame goes to increased spending and 2/3 to the Bush tax cuts

Max Sawicky isn’t that concerned with the size of the deficit:

Today’s deficit number is a yawn for we sad few who take the trouble to follow this. More annoying is what the Bushies are saying.
Quoth new OMB Director and reputed whiz kid Josh Bolten: “Restoring a balanced budget is an important priority for this administration,” he said, “but a balanced budget is not a higher priority than winning the global war on terror, protecting the American homeland, or restoring economic growth and job creation.”
Only trouble is, the war cost for FY2003 is only $90 billion, and the DoD increase is $80 billion. The rest is due to you know what.

but does think the composition of the deficit should be changed:

The real problem with the deficit for this and next year is composition. Given the opportunity, I wouldn’t reduce it a penny. Instead I would redirect the tax cuts to the working class, reserving a nice chunk of change for aid to state and local governments. This sort of tax cut could be designed to limit long-term deficit effects. The latter are the real problem, insofar as there is one. Now is a clear case where the distribution of the tax burden has an urgent macroeconomic policy significance.
Otherwise the Democrats’ harping on this has limited, if non-zero, value. Given the podium, I would emphasize the jobs gap, the holes in the Medicare drug benefit, children left behind by the tax cuts, and the potential problems with Medicare financing.

Kevin Drum agrees that the real problem is in the future:

By 2007 the economy should be booming and the government should be planning to run modest surpluses to cool things down a bit. Instead, it’s deficits forever, because seemingly nobody in this administration cares a whit about anything beyond the next election.

Good or bad the deficits will be used mercilessly to hammer bush and this along with the administrations repeated fabrication of reality will lead to a change of administration in 2004. History will judge whether this change will be good or bad.