TEXT OF COMMENTARY

SCOTT JAGOW: Congress just gave President Bush an unwelcome surprise: It refused to normalize trade relations with Vietnam. The issue could come up again next month. But after that, the Democrats take control of Congress and trade deals could be harder to come by. As for the Democrats, Commentator David Frum says once they take the reigns, they should move fast.

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DAVID FRUM: Once the Democrats are done with votes on raising the minimum wage, controlling Medicare drug prices and perhaps pushing through a phased withdrawal from Iraq, they're going to get really ambitious.

It'll be on to balancing the budget via higher taxes, a national health care and new labor laws to make it easier for unions to sign up new members.

In other words: the strategy is start economically moderate, win some fights, and then get economically radical.

And yes sometimes that does happen. The Democratic Party won a huge congressional victory in 1930 and then two more right after that. They got bolder with every victory.

More often, though, the forces of inertia grind a new majority party down, leeching its energy and idealism. That's the story of the Congressional Republicans, and especially the House Republicans, between 1995 and 2006.

Or compare the record of Senate Republicans in the first two years of their Reagan majority, 1981 and 1982 to their inaction in the following two years.

Moral: Almost all the big things a party does, it does in the first weeks and months after a triumphant election victory.

So, attention Democrats: If you want to do something dramatic with your new majority, you had best do it now.

But there's one little catch: a second rule of politics. It is incredibly dangerous for a political party to do anything major for which it has not explicitly asked permission in the preceding election.

The classic example: The Clinton tax increase of 1993. Having campaigned on a middle-class tax cut, the Clinton administration hiked taxes instead and promptly lost the House and Senate.

It's like Babe Ruth's famous called shot: In politics, a run only counts if you tell the fans where you're planning on putting the ball.

So if you run as a moderate party, you'd better remember to govern that way.

JAGOW: David Frum is a resident fellow at the American Enterprise Institute.