Dear Senator Obama …

Your campaign has been brilliant. It has given you more support and more momentum than most analysts expected a year ago. Keeping things simple and vague has worked so far, and it might work all the way to the White House. "Change you can believe in" is a great all-purpose slogan. It allows every person to fill in his or her own interpretation of what it means. In some ways, it's reminiscent of Jimmy Carter's 1976 promise to run "a government as good as the American people."

The challenge you will face in the next few months is stark. Do you want to remain vague? You might win—but you might find that, in winning, you have a "victory of personality" with no real policy consequences. Or do you want to provide specifics? If so, your victory could be a clarion call from the American people to Congress to join you in achieving your goals.

I participated in two successful "change" campaigns: the Reagan revolution of 1980 and the "Contract With America" in 1994. Both were built around a limited number of powerful, specific proposals. As a freshman congressman in 1980, working in coordination with the Reagan presidential campaign, we selected five popular themes we knew would help our candidates get elected and create momentum for President Reagan's bold agenda. The clarity of these five positions (the two most important were a three-year, 30 percent tax cut and strengthening the military) helped our candidates in the closing weeks of the campaign. We won the presidency, six seats in the Senate, 33 in the House—and joined with a minority of Democrats to pass the key measures into law.

In 1994, House Republicans had been in the minority for 40 years. We needed to do something dramatic. So instead of a traditional platform of vague commitments ("We believe in …"), we offered a clear program of specifics ("In the first 100 days, we will …"). We also enjoyed the advantage of positive historical trends. Already, there was an emerging consensus in favor of welfare reform, tax cuts, a stronger military and a balanced federal budget. Every item in the "Contract With America" had support from the vast majority of Americans.

Can you find five big changes that are substantive, popular—and can rally Democrats from the House and Senate to join you on the Capitol steps in September or October? If you cannot, you should question if you'll be able to deliver on your "change" slogan. Your campaign advisers may not care about that. Their instinct will be to win the election and leave the difficulties of governing up to you. But if you want to be a genuine historic agent of change "we can believe in," then you have to look beyond Election Day.

President Carter never understood this. When his vague campaign of "trust me" and "a government as good as the American people" came to Washington, it ran into a Democratic Congress that didn't trust him and that wanted a government that was good for the Congress. Carter, like many outsiders who become president (including the current White House resident), greatly underestimated the institutional strengths of the Congress. Many state legislatures meet very rarely. Georgia was like that when Carter was governor, and the Texas legislature only meets every other year. This gave Governor Bush a considerable misunderstanding of the depth of institutional trouble he would face in Washington.