THE HUGE EXPANSION of government overseen by the supposed party of small government has provoked a conservative backlash. The Heritage Foundation, which is usually respectful of Republican Party officeholders, recently noted that the party's ascendancy has coincided with an extraordinarily expensive Medicare prescription drug bill, the most costly farm bill in modern history, a 51 percent increase in spending on veterans and an increase in the annual number of pork projects from 6,000 in 2001 to 14,000 this year. Rank-and-file Republican House members are fed up with this unconservative record; on Wednesday they rebelled against Majority Leader Tom DeLay's scheme to have a big-spending ally keep his throne warm while he fights a criminal indictment. But the conservative revolt should logically be taken a step further. It should target President Bush.

When they are at their most timid, which means frequently, critics of government profligacy are content to blame "the system." They point to the pressures on members of Congress to grasp for favors for their districts. They invoke the old truth that special interests hire lobbyists to fight for subsidies while the public that pays for them goes unrepresented on K Street. But blaming systemic forces for political cronyism is like blaming crime on societal forces such as poverty. It's part of the explanation, but it isn't the whole one. Conservatives should know this better than anybody, since they believe most ardently in personal responsibility.

Who should be held responsible for runaway government spending? Mr. DeLay is certainly a good place to start. His governing principle was not to stand on principle but rather to rain taxpayers' money on every lobby that could return the favor with campaign contributions. But the biggest responsibility lies not with any member of the legislature but with Mr. Bush. Unlike senators and House members, the president represents the whole nation; he is supposed to defend the general interest against particularist claims. Moreover, he has the power to do so. If Congress serves up wasteful bills, the president can veto them.

Mr. Bush has been too cowardly to do that. He is the first president since John Quincy Adams to have served a full term without once exercising his veto, and his second term has so far been no different. This summer Mr. Bush promised to veto the transportation bill if it cost more than $256 billion. His threat brought the bill's size down quite a bit, but in the end he caved and signed a package that cost $295 billion. Why did he blink? Doesn't his administration pride itself on defending the power and prerogatives of the presidency? Mr. Bush's father had the courage to veto 44 bills in four years, and President Ronald Reagan once vetoed a transportation bill because it contained about 150 pork projects. But the bill that Mr. Bush just signed contained at least 6,000 pork projects.

The president's defenders plead that it's hard to veto bills when his own party controls Congress. But as the conservative commentator Bruce Bartlett points out, this defense is nonsense. President Franklin D. Roosevelt held office at a time of huge Democratic Party majorities in Congress, but that didn't stop him from vetoing a record 635 bills. Presidents John F. Kennedy, Lyndon B. Johnson and Jimmy Carter also coexisted with large Democratic majorities, yet Kennedy vetoed 21 bills during his short presidency, Johnson vetoed 30 and Carter vetoed 31.

The truth is that there is nothing to stop Mr. Bush from wielding his veto -- witness the fact that the administration threatened Friday to veto a defense bill if, among other potential offenses, it contained language outlawing cruel and inhuman treatment of foreign detainees. But while Mr. Bush cares fervently, and scandalously, about the imperative of keeping inhumane practices legal, he does not care as much about waste of taxpayers' money. This is why he has not made vigorous use of his veto to restrain the growth of pork. This is why an anti-spending backlash that focuses only on Mr. DeLay is missing its main target.