Sen. Ben Cardin (D-Md.) at the the Annapolis Rally for Healthcare at Lawyer’s Mall on July 29. (Matthew Cole/The Baltimore Sun via Associated Press)

Chelsea Manning, Jerome Segal, Rikki Vaughn are candidates for the Democratic nomination for the U.S. Senate from Maryland.

In less than three weeks, the Democratic Senate primary will be held in Maryland. And to this point, voters haven’t been given the opportunity to hear the candidates discuss the critically important issues facing the state. We, who are challenging incumbent Sen. Ben Cardin, want to know where he has been. He’s been missing in action, and we want him to engage with us in a vigorous debate.

We are astonished and disappointed that the media, which has paid enormous attention to the Democratic primary for governor, has largely ignored the Democratic Senate primary. We find this indifference hard to understand. It is clear that the media believe that the race isn’t worth covering because Cardin’s reelection is a done deal.

Maryland voters certainly want change. Many probably are unfamiliar with key aspects of Cardin’s record. For instance, few Maryland Democrats know that he voted against former president Barack Obama’s nuclear deal with Iran, a deal very strongly supported by Democrats.

The media view that Cardin’s reelection is a done-deal is self-fulfilling. One hears often about the “advantages of incumbency,” but the key advantage of the incumbent is that he or she is well known, while the challenger or the basis of his or her challenge is not. For the challenger, being unknown is political death. How is the challenger to make his or her case to the public?

The media’s bias toward the status quo enables Cardin to stay in the shadows. If there were a debate, the three of us would expose that fact that he’s accomplished little during his three decades in Congress. It would also allow us to shine a light on how he has flip-flopped on numerous important issues, especially in the foreign policy area. The media’s failure to cover the primary reveals a glaring bias toward the status quo, preventing a challenger from being heard by the voting public.

This disregard by the media has a corrupting effect. It promotes disinterest in a civil society. And such is the case here in Maryland. Not one progressive organization in the state has endorsed any candidate in the primary. And while multiple debates were scheduled for the gubernatorial race, not one civic organization, or  media organization and not the Democratic Party itself proposed a debate between us and Cardin.

Accordingly, we three have come together to call on Cardin to join with us in debating the issues facing the state and our country. We call for an opportunity for each of us to address three questions: 1) Why are we running? 2) What is our agenda? and 3) Why are we the best choice when voters go to the polls?  We ourselves will, in our answers, frame the issues discussed during the debates and we will respond to what the others have said.

So senator, this is our call to you: Will you join us in an open and extended presentation of ideas before the Maryland electorate?