The Senate this week seems likely to pass an earmark-laden, $410 billion omnibus spending bill leftover from the last fiscal year. Even though he is in no way responsible for this mess, we hope President Obama will veto the bill the moment it lands on his desk.

This bloated bill increases federal spending by 8 percent -- even as the government forecasts a record-shattering, $1.75 trillion deficit for 2009. It also contains no fewer than 9,000 earmarks. We're not opposed to all earmarks on principle, but too many of these would fail the laugh test even if the U.S. economy was humming.

Perhaps the most compelling of Obama's campaign pledges was his vow to change the way Washington works. The omnibus bill is a perfect illustration of the nexus between special interests, campaign contributions, and compliant members of Congress. By vetoing it, the president can serve notice that he's serious not only about ending business-as-usual in Washington, but also about fiscal discipline.

This would be a particularly reassuring signal now, as Americans are still digesting the Obama administration's audacious 2010 budget. It spends prodigiously to avert a deeper economic calamity, funds major new initiatives on health care and clean energy, and restores progressive taxation in America.

Despite some reservations, we generally support these goals and, in the absence of greater detail, are willing to give the president the benefit of the doubt at this point. But the change America needs doesn't simply entail big spending increases. It also requires reforming broken public sector systems and policies, and it requires a swift return to fiscal discipline as soon as the economy turns up. Otherwise, U.S. prosperity could drown in a rapidly swelling ocean of national debt.

Sooner or later, Obama will have to face down the forces in Washington that propel chronic overspending, irresponsible tax cuts for the people who need them least, and massive borrowing from foreign lenders. He might as well start now.

Will Marshall is president of PPI.