"Let me say this clearly, because we hear all the time that NASA has 'abandoned' ExoMars," Bolden said. "We have not abandoned ExoMars, and the Electra payload is an example of our continuing high interest in the mission."
ExoMars Trace Gas Orbiter, NASA.gov
"NASA will not be moving forward with the planned 2016 and 2018 ExoMars missions that we had been exploring with the European Space Agency. Instead, we will develop an integrated strategy to ensure that the next steps for Mars exploration will support science as well as human exploration goals."
Keith's note: Note: Electra is a UHF radio/relay on MRO. It is already in orbit at Mars. As such, it doesn't take much "high interest" on NASA's part to allow ExoMars or any other mission to use it - as long as it still works.