Like pardons and executive orders, vetoes are among the cherished privileges of the Oval Office. Ike liked them. So did presidents Truman and Cleveland - and both Roosevelts. But apparently not George W. Bush. In fact, well into the fifth year of his presidency, he has yet to issue a single veto.

Although the streak could end next month - Mr. Bush is threatening a veto if Congress eases his restrictions on federal funding for stem-cell research - the Bush era thus far underscores a historically high-water mark of collegial cooperation between Congress and the White House, experts say.

"We're pretty close to a parliamentary government," says G. Calvin Mackenzie, professor of government at Colby College in Watervillle, Maine, referring to Congress's close alignment with the executive branch. "We don't have much recent history with that."

Other presidents have enjoyed majority support in Congress. But few, if any, have gotten the level of disciplined backing that Mr. Bush gets from House and Senate Republicans.

"There is unusual coherence between Republicans in Congress and the president," Professor Mackenzie adds. "So there's very little getting to his desk that hasn't been pre-approved by the Republican leadership."

On many major bills that Bush has signed - No Child Left Behind and tax relief, for example - the veto was never a consideration because the White House itself had proposed the legislation. Yet on dozens of other bills, the president has become a rubber stamp for a spendthrift Congress, betraying his campaign image as a fiscal conservative, critics say.