An earlier report by Ken Rosenthal of FOX Sports has revealed that the Washington Nationals are interested in Chicago White Sox closer David Robertson. It’s pretty clear why due to their need for a closer but the cost is what remains unclear. The Nationals traded away several of their best prospects to the White Sox previously in the Adam Eaton deal. Now left with fewer options, what might a Robertson trade package look like?

Victor Robles is untouchable and not someone the Nationals should trade away for anything short of a guaranteed World Series victory. His involvement in any trade is unlikely.

Other top Nationals prospects are not nearly as safe. Pitcher Erick Fedde is the most notable player who could get dealt to the White Sox in exchange for Robertson. As the only other Nationals prospect within MLB’s top 100 list, Fedde is an important part of the team’s future. He is their ammunition in the minor leagues to help out the rotation or bullpen within the next two years. It would certainly be heartbreaking to see him traded.

Robertson for Fedde straight up is possible but unlikely. The White Sox know the Nationals are desperate. They are not about to sell him low. If Fedde is involved in the trade it would mean another prospect goes with him.

Another name to pay attention to is shortstop prospect Carter Kieboom. Last year’s first-round draft pick happens to play the same position as the Nationals’ young star, Trea Turner.

There is an obvious way to work around this. The Nationals could groom Kieboom to play somewhere else. Second baseman Daniel Murphy will not be around forever. Third baseman Anthony Rendon might already be a free agent by the time Kieboom is ready for big league action. This could lead to the Nationals playing him at second base or third base more often in the minors.

At this point, it’s worth asking ourselves if Fedde and Kieboom is a big enough package to land Robertson.

A lot of this is dependent on what the White Sox want out of the deal. If free salary is a major concern then they might settle for just Fedde. If the desire is greater, Fedde and Kieboom could be enough. The pair is also probably far more than the Nationals should give up for a closer who appears to be on the decline.

Pitching prospect Austin Voth is one final name worth mentioning as a piece the White Sox could have interest in. Considering Fedde seems to have a higher place within the Nationals’ organization, Voth looks rather expendable. In which case, pairing him with Kieboom could be a tempting duo that both teams accept.

Robertson should remain on the Nationals’ radar. No deal is imminent, but this could soon change should the Nationals decide to go for broke.

Tim Boyle is a Staff Writer for Outside Pitch MLB covering the Washington Nationals. Follow Tim on Twitter.