WASHINGTON — On Wednesday, as Speaker Newt Gingrich (R-Ga.) calls the House in the 104th Congress to order, he will look off to his left and see arrayed before him columns of freshly minted Republican troops, disciplined, determined and poised to make rapid and sweeping changes in America's political and cultural landscape.

In what Gingrich hopes will be a 100-day legislative blitzkrieg, the GOP plans not only to cut taxes, revamp welfare and reduce regulation, but to overhaul government itself.

That is the battle plan. But as one of America's best-loved modern generals, Colin L. Powell, said in the wake of the Persian Gulf War: "No battle plan survives contact with enemy."

The U.S. government, balanced finely on three pillars, has withstood the determined march of many revolutionaries before.

The newly ascendant Republicans, historians agree, are certain to make a historic mark on Congress and on the laws it passes. But just as certainly, much of the lawmakers' energies will be absorbed by a governmental structure designed to change slowly and to withstand repeated legislative batterings along the way.

"You can be in the biggest hurry in the world, but we have a government that says: 'Calm down, slow down, let's think about this,' " said Joel Silbey, professor of history at Cornell University. "Don't be taken in by the energy of this Congress. . . . This juggernaut is going to encounter speed bumps."

Some of those speed bumps were put in place by the drafters of the Constitution, and some have been carved into place by 206 years of parliamentary operations. Ironically, other impediments that will limit Congress' ability to act at will are being put in place by Gingrich--the very man who is so intent on dominating policy-making for the next two years.

Undaunted, Gingrich and his allies have done more than lay down a challenge to President Clinton's policies: Symbolically, said Yale University's David Mayhew, they have challenged the power of the presidency itself. In their "contract with America," Republican lawmakers have appropriated the concept of an agenda for the first 100 days of office--a political device that began with President Theodore Roosevelt and reached its romantic apotheosis with the John F. Kennedy Administration.

"He's stealing a script from presidents . . . and that's the first time that's ever been done," said Mayhew, a political scientist and author of "Divided We Govern." "For a congressional party to do that is a new thing."