ROGERS, Ark. — President Bush admonished Congress today for failing to send him a single spending bill yet, and warned lawmakers to trim their plans or face rejection.

“You’re fixin’ to see what they call a fiscal showdown in Washington,” Mr. Bush told a friendly audience in this northwest Arkansas community.

“The Congress gets to propose, and if it doesn’t meet needs as far as I’m concerned, I get to veto,” Mr. Bush said. “That’s precisely what I intend to do.”

The budget year began October 1, and federal agencies are operating on a stopgap bill for now. Congress has not yet agreed on the 12 spending bills that keep the government running.

“Congress needs to be responsible with your money and they need to pass these appropriations bills — one at a time,” Mr. Bush said, roaming the stage. “And then we can work together to see whether or not they make fiscal sense for the United States.”

Mr. Bush never vetoed a spending bill when his party ran Congress, but he’s dug in for a challenge now. He said the Democrats’ plans would raise taxes and prevent the nation from balancing the budget.

Conservative House Republicans appear to have the votes to sustain his promised vetoes.

For a president short on domestic victories, the White House sees fiscal discipline as a winning argument for Mr. Bush: a chance to label the opposition in tax-and-spend terms.

The Democratic majority leader in the House, Rep. Steny Hoyer of Maryland, said Mr. Bush was in no position to offer a lecture on fiscal responsibility. He accused Mr. Bush of engaging in a vain attempt to play to his party’s conservative base by promising vetoes.

“This is not a fight about spending,” Mr. Hoyer said. “It’s a fight about our priorities as a nation — whether we adequately fund education, medical research, Head Start, clean water programs and health care for our veterans and men and women in uniform.”

In the budget stalemate, Democrats are pressing to spend about $22 billion more on domestic programs than Bush wants.