Barack Obama clinching the Democratic nomination for president holds some interesting implications for leading Pennsylvania Democrats who supported U.S. Sen. Hillary Clinton of New York in the primary.

As the process of selecting running mates unfolds, one thought about the Democratic ticket is uppermost in our minds -- anyone but Gov. Ed Rendell.

That has little, if anything, to do with Rendell, per se, though it will be interesting to see how enthusiastically he and other prominent Clinton backers, such as Allegheny County Chief Executive Dan Onorato and Pittsburgh Mayor Luke Ravenstahl, support Obama from here on out -- and how such leading Dems' performance in the campaign will affect how Pennsylvania is treated if Obama wins in November.

Put it this way: We doubt even Rendell's harshest critics would relish two years or so of Lt. Gov. Catherine Baker Knoll -- a woman with a solid record of making awkward statements at inopportune times -- occupying the governor's mansion.

Republican John McCain's running mate selection process is worth watching, too. But remember that vice presidential candidates rarely have much influence on the outcome of presidential elections, which are about the top of the ticket.

So we're pleased that voters will have a clear choice between candidates of different generations who have different views on Iraq, the economy and other issues.

Given the historic implications of Obama's candidacy, we hope that, whatever the outcome at the polls, the campaign leaves America a little further ahead in its long journey toward realizing Dr. Martin Luther King Jr.'s dream.

It took both parties longer than expected to settle on nominees who were not the early favorites, but along the way, many voters were energized, many people voted for the first time and, among the attack ads, a lot of serious discussion of issues did occur during the primary season.

We hope those trends of rising interest and participation continue until voters go to the polls in November -- and after -- and that as many Americans as possible take part in deciding an election that surely will hold the interest of historians for decades to come.