Welcome back, members of the final session of the 99th Congress of the United States. You're going to make history whether you like it or not. And no matter what you say collectively and publicly about the great political challenge now before you, the betting here is that few among you like it.

You've been thrust, or have allowed yourselves to be thrust, into a position of rendering historic political judgment. There appears no way to escape it.

Your challenge involves much more than dealing with budget-deficit politics in a high-stakes election year, that familiar list of what to do about the self-imposed Draconian dictates of Gramm-Rudman-Hollings and whether to raise taxes and/or cut/keep high levels of defense spending. The challenge is this:

In your hands rests the determination of whether Ronald Reagan has led a revolution that alters the fundamental role of the federal government in American life. Those are the real political stakes of '86. In one way or another, your actions this year will signal whether Reagan's presidency has brought profoundly lasting political change or merely represents a correction in the governmental course Americans have favored throughout this century.

Exactly five years ago this week, one month into his presidency, I wrote here about the opening stages of what I and many others then called "the Reagan Revolution." Invariably, the comparison drawn was between the political approaches of Franklin D. Roosevelt and Reagan, between FDR's fashioning of the modern political welfare state and Reagan's attempt to unravel it. Seen now in longer perspective, a better analogy would have been between Reagan's ideological approach and that of the other great Roosevelt, the Republican one.

Today, Theodore Roosevelt seems remembered most as a jingoistic American who swaggered about, clicking his prominent teeth while brandishing a big stick and dispatching the Great White Fleet around the world intent on fulfilling the nation's manifest destiny of gobbling up remnants of colonial empires. He was the cowboy come of age in the new century, the American imperialist astride what many arrogantly believed to be the dawning of the "American Century."

It was, at best, a ludicrous parody of one of the wisest statesmen and strongest leaders to occupy the White House and nowhere more so than in the rendering of what he stood for, and achieved, politically.

The Republican Roosevelt led the fight for progressive domestic legislation, for expanding the national government's role in previously untouched areas of U.S. life. Teddy's "Square Deal," precursor of his cousin Franklin's "New Deal," put government in the arena of regulating banks, industries and railroads; breaking trusts and monopolies; establishing pure-food-and-drug laws; conserving and preserving national lands and resources; promoting social and industrial justice, and seeking through law to provide citizens with greater protection in public health and welfare.

As one of his ardent disciples, small-town Kansas editor William Allen White, later wrote:

"Our social philosophy simmered down to this: the national income must be shifted so that the blessings of our civilization should be more widely enjoyed than they were. To make that shift, what Colonel Roosevelt called 'predatory wealth' or 'aggrandized capital' should have its claws pared, its greed checked, its rapacity quenched so far as is humanly possible. And the shift or redistribution of national income should be achieved by using government where necessary as an agency of human welfare. Lord, how we did like that phrase, 'using government as an agency of human welfare'! That was the slogan . . . boiled down to a phrase."

Give Reagan credit for consistency and strength of purpose. His newest budget, now unwelcomingly before Congress, continues to an astonishing degree his all-or-nothing political approach. It further assaults and reduces the federal role in domestic life while strengthening the role of the Defense Department. It proposes to sell off precious national assets and everywhere celebrates the private over the public interest.

If endorsed by this Congress, it will mean rejection of basic political principles that have dominated American life since the time of Theodore Roosevelt. Now that's a revolution.