WASHINGTON -- President Barack Obama on Tuesday called for legally binding measures to enforce government spending restraint, but his congressional allies -- and his own actions -- threatened to undermine his message of fiscal discipline.

President Barack Obama speaks to House Majority Leader Rep. Steny Hoyer (D., Md.) on Tuesday at the White House. Reuters

Mr. Obama proposed to give "pay-as-you-go" budgeting rules the force of law, which would require Congress to offset entitlement-spending increases and tax cuts, either with spending cuts or tax increases. But critics say the proposed rules are riddled with loopholes and would have little impact.

House appropriators on Tuesday unveiled spending numbers for the coming fiscal year that push up domestic outlays by 10.4%, after lawmakers used gimmicks to get around the pay-as-you-go rules Mr. Obama is embracing.

"This is like quitting drinking, but making an exception for beer and hard liquor," said Maya MacGuineas, president of the Committee for a Responsible Federal Budget, a nonpartisan watchdog group.

Senate Budget Committee Chairman Kent Conrad, a North Dakota Democrat, said he has "serious concerns" about exemptions to the deficit curbs that would run to trillions of dollars.

Over the first five months of his administration, Mr. Obama has struggled to balance his embrace of big spending to combat the financial crisis and recession with pledges to curb the budget deficit.

The president has pledged to cut in half the $1.3 trillion deficit he inherited by the end of his term, in part through restoring 1990s-era measures to enforce spending discipline, such as those announced Tuesday.

"The reckless fiscal policies of the past have left us in a very deep hole, and digging our way out of it will take time, patience, and some tough choices," Mr. Obama said in the White House East Room, flanked by Democratic leaders and members of the fiscally conservative Democratic Blue Dog coalition.

Yet the president has also signed a $787-billion stimulus bill and committed more than $60 billion to bail out Chrysler LLC and General Motors Corp. The deficit is projected to balloon to $1.8 trillion in the fiscal year that ends Sept. 30.

Pay-as-you-go was first implemented as part of the 1990 budget deal between congressional Democrats and then-President George H.W. Bush, when Mr. Bush broke his "no new taxes" pledge. Congress allowed the rules to lapse in 2002.

Under the pay-go proposal Mr. Obama outlined Tuesday, any policy change that increases spending in so-called mandatory entitlement programs, such as Medicare and Social Security, would have to be offset by equivalent spending cuts or tax increases. Tax cuts would also be covered. If Congress failed to offset such costs, automatic, across-the-board spending cuts would kick in.

But the administration is leaving itself sizable loopholes. For example, the cost of extending most of former President George W. Bush's tax cuts wouldn't have to be offset, nor would the cost of legislation keeping the alternative minimum tax from expanding. And Congress wouldn't have to offset the cost of legislation&mdash;passed every year&mdash;to ensure that planned cuts to physicians under Medicare don't actually happen.

Those exemptions spare lawmakers from having to find $2.5 trillion in offsetting spending cuts or tax increases over the next decade.

White House Budget Director Peter Orszag said it was "implausible" that Congress would ever allow all of the Bush tax cuts to expire, the AMT to explode or doctors to be hit by severe reimbursement cuts, as current law allows.

Perhaps the biggest loophole is that the rules wouldn't apply to discretionary spending, which will amount to $1.4 trillion in fiscal year 2010, about 40% of the budget. In the 1990s, that spending was subject to strict caps. But since those caps, after several years of effective enforcement, ended up being routinely flouted, White House officials say they are not seeking their reinstatement.

Congress is already finding ways around the rules. The budget resolution passed this year, for instance, approved a $2 billion increase in low-income heating assistance as an entitlement change, which would require the painful offsets. But the resolution allowed appropriators to tack that money onto their total "discretionary" spending, no offsets needed. On Tuesday, the appropriators received broad spending allocations, which included the $2 billion for low-income heating assistance without offsets.

In all, the appropriators were given allocations that would allow domestic discretionary spending programs to rise by $39 billion. Including security and foreign aid, discretionary spending would rise by $75 billion, or 7.5%.

White House aides said there is still time to bring those figures down.

Write to Jonathan Weisman at jonathan.weisman@wsj.com