The only certainty in the emerging presidential race is that only one candidate will win. And after the election is decided, few people will want to focus on the losing candidates. Some of the candidates will fade from public view forever, becoming historical footnotes.

But C-SPAN, the nonprofit public affairs channel sponsored by the cable television industry, has a new series that focuses on memorable losers in presidential races throughout American history. “The Contenders” began this past week and will continue each Friday night at 7 unless pre-empted by live coverage of Congress.

The point of the show is that even candidates who lose presidential races can have a strong role in shaping the course of the nation.

Among those featured will be Henry Clay, George McGovern and Ross Perot.

This reminded us of something two-time presidential candidate Adlai Stevenson, who never achieved the presidency, said about losing after one of his races: “There are things more precious than political victory; there is the right to political contest.”

Losing candidates give voters a choice, and choice is critical in a healthy republic. That’s why the also-rans in presidential races — and in all political races — deserve some credit.