The White House struck a hard line on spending Friday, warning Democrats in Congress that their efforts to boost domestic programs such as education would provoke vetoes this fall.

In a letter to lawmakers, White House budget chief Rob Portman vowed that President Bush will veto appropriations bills — the 12 annual spending measures funding Cabinet agency budgets — that bust Bush's budget targets.

The missive suggests, however, that Bush would permit Congress to move some funds from a record $50 billion Pentagon budget increase to domestic programs so long as lawmakers respect an overall "cap" on appropriated spending of $933 billion. The other two-thirds of the budget pays for benefit programs such as Medicare, Social Security and farm subsidies, as well as interest on the national debt.

Portman's letter came as a $2.9 trillion congressional budget blueprint for next year is in House-Senate talks. The blueprint sets an overall limit for the 12 appropriations bills. Democrats have signaled they'll add more than $20 billion for domestic agency budgets, an above-inflation increase of about 5 percent.

"The top line the president submitted is the top line that we want to hold," Portman told The Associated Press.

The hard line comes as Democrats and Bush are also doing battle over funding for the war in Iraq. While much attention has been focused on Democratic efforts to force troop withdrawals, Bush also vetoed a $124 billion war funding bill over more than $20 billion in congressional add-ons such as aid to farmers.

"The administration does not believe that the first step to a balanced budget should be a substantial increase in federal spending," Portman wrote.

Democrats seemed unimpressed by Bush's warnings.

"This is the same guy who's squirted away almost $600 billion on a stupid war and this is a guy who's riding at 28 percent in public opinion polls," said House Appropriations Committee Chairman David Obey, D-Wis.

"His word is not the last word," said Senate Appropriations Committee Chairman Robert Byrd, D-W.Va. "The White House should step back from this petty game of brinksmanship."

Bush has long battled with senior members of Congress' Appropriations committees, particularly over his attempts to freeze domestic agency budgets.

But even Republicans tapped the defense budget to bolster domestic programs, and Democrats may ultimately raid Bush's eye-popping $481 billion Pentagon budget request — an 11 percent increase — to bolster domestic programs, which Bush's budget would essentially freeze at current levels.

Congress' annual appropriations process typically dominates House and Senate floor schedules for the summer months as lawmakers debate budgetary minutia.

The bills also provide a forum for numerous policy squabbles on topics such as abortion, relations with Cuba and whether to permit U.S. residents to purchase less expensive prescription drugs from other countries such as Canada.

Bush has in fact won most of those battles, though some GOP conservatives have faulted him for not vetoing a single spending bill in his first six years in office.

Bush has in the past relied on powerful GOP leaders such as former Speaker Dennis Hastert, R-Ill., to impose discipline on appropriators — a luxury he does not have now that Democrats are in charge on Capitol Hill.

Now, Bush is likely to have to veto numerous bills to hold the line on spending and fend off policy "riders" such as lifting the ban on U.S. citizens traveling to Cuba.

But such vetoes may lead to yet another foot-tall "omnibus" spending bill this fall as the White House and Congress stitch together post-veto compromise measures into a larger bill or bills.