St. Paul Mayor Randy Kelly took a major hit in last week's primary election. The common wisdom says it was the price he paid for endorsing George Bush in 2004.

What could the guy have been thinking? Kelly knew his decision would damage him politically. And he knew he had little chance of swaying St. Paul voters to Bush. Heavily Democratic Ramsey County hasn't voted for a Republican for president since Calvin Coolidge in 1924.

At the time, Kelly gave two reasons. First, he believed that America was at a critical point in the war on terror, and that George Bush would see it through to completion. In addition, Kelly said he was fed up with "negative politics" -- Democrats' hatred of Bush, Republicans' hatred of Clinton and the bitter, paralyzing politics of vitriol.

At the national level, said Kelly in a guest column, "I am sure that continuity of government will produce better results than an anger-motivated transition of power."

Political observers looked everywhere for a hidden motivation, a backroom deal. But they came up empty. Could it be that Kelly was sincere in invoking sentiments he attributed to John Kennedy: "When there is a conflict between what is best for my party and my country, my first obligation is to conscience"? Was Kelly's decision that rare thing: an act of principle, a profile in political courage?

Today, we tend to see politicians as a cynical breed. We think of most as taking few risks, and all too frequently basing decisions on daily tracking polls.

But there are elected officials who believe that leadership requires more. It's said that a close adviser to Ronald Reagan once recommended that he abandon his opposition to legalized abortion because a majority of Americans supported abortion rights to some extent. Reagan responded that a majority of the people may disagree with him but 100 percent of the people want a president who will say what he thinks.

Randy Kelly has been speaking his mind for years, and his problems with St. Paul's DFL leadership started well before he endorsed Bush. Increasingly, special-interest groups dominate both the Democratic and Republican parties. In the St. Paul DFL, heavy hitters include public employees, teachers and abortion-rights supporters. These groups impose litmus tests: Candidates must support abortion rights and be dovish on foreign policy. Randy Kelly -- abortion opponent, strong on defense, and fairly fiscally conservative -- is out of step.

Democrats tolerated far more diversity until recent years. For example, prominent senators such as Henry (Scoop) Jackson and Sam Nunn advocated a vigorous American foreign policy without serious political damage. Minnesota had prominent public officials such as A.M. (Sandy) Keith, a former state senator, lieutenant governor and chief justice of the state Supreme Court. Keith was a fiscal conservative and strong on defense without paying a significant political price.

Among Democratic leaders, such tolerance is evaporating. Most famously, in 1992, the party banned Pennsylvania governor Bob Casey from speaking at its national convention because of his opposition to abortion. Intolerance on a range of issues led Norm Coleman to leave the DFL in the '90s.

Like the Democrats, the Republican party has become increasingly ideological. Yet it tolerates mavericks such as John McCain, and liberals such as Sens. Arlen Specter and Lincoln Chafee. Democrats have no parallel to Rudy Giuliani, a man who crosses his party lines on abortion and other social issues, but retains enormous stature and popularity.

By rejecting Kelly -- a successful sitting mayor with a vibrant vision for St. Paul -- the DFL is sending a message to voters: This party has no room for those who don't hew to a narrow, ideological party line. Party officials have descended to pettiness to enforce conformity. Last month, according to news reports, they voted to exclude Kelly from a customary invitation to serve ice cream at the party's State Fair booth.

Obviously, the DFL's narrow-mindedness poses a problem for Randy Kelly. Yet in 2001, he won the mayor's seat without the party's endorsement. In last week's primary, Kelly struck out with DFL stalwarts. But he will work hard to reach a cross-section of voters in the general election.

By rejecting Kelly, the DFL is shooting itself in the foot. American political parties have grown significantly weaker in recent years. Their base among voters has contracted as they have become more ideological. Since the 1970s, the turnout at both Minnesota's Democratic and Republican precinct caucuses has declined dramatically. Today more than one-third of national voters call themselves independents and tell pollsters that neither party reflects their views exactly.

Not all St. Paul voters agree with Randy Kelly about George Bush and national security policy. But 100 percent of them should be glad they have a mayor who acts on his convictions with courage.