USA Today

Tea party Republicans are steaming about last week’s Senate primary runoff in Mississippi, where incumbent Thad Cochran won a surprising victory over a more conservative challenger, thanks in part to Democrats who crossed over to vote for Cochran.

That result, the tea partiers argue, shows the folly of “open primaries” — those that allow Democrats to vote in GOP contests, and vice versa.

At other times, liberal activists have made the argument against such elections. In 2010, they were outraged when Alvin Greene, an unemployed Army veteran who never bothered to campaign, was chosen as the Democratic candidate for the U.S. Senate in South Carolina. The result was seen as the handiwork of Republican mischief designed to ensure that the GOP incumbent did not face a credible challenger in the general election.

As a general rule, anything that the far right and the far left both decry is a decent idea. And so it is with open primaries. While they can be the subject of dirty tricks, they are more likely to produce candidates who are moderate enough to win in general elections and be more effective in office.

The very people who cross over are often the very people a party most needs to attract. In Mississippi — where Democrats were allowed to vote in a GOP runoff as long as they hadn’t cast a Democratic ballot in the primary three weeks earlier — African-Americans made the difference.

If the GOP is to remain a viable party in national elections, it will have to attract more black, Latino and Asian-American voters. Chris McDaniel — the tea party-backed candidate who lost to Cochran — could have tried to appeal to African-Americans. He chose not to. In fact, black Democrats in Mississippi were so worried about McDaniel that they went to the trouble of voting against him in a Republican election.

Democrats could benefit from open primaries as well. While their more diverse and splintered nature has not led to nominations of as many unelectable candidates, a hard-core liberal base seems intent on changing that.

The biggest winners in open primaries are voters. The electorate is growing more polarized, as evidenced by a recent study by the Pew Research Center. Even so, more people still describe their political views as mixed (39%) than as liberal (34%) or conservative (27%).

— USA Today