Rep. David Cicilline (D-RI)

For now, Democrats can only ask for the "tapes" that President Donald Trump has suggested may exist of his conversations with fired FBI Director James Comey. But if the party takes back the House next year, it can subpoena them.

The supposed "tapes" are just one of a number of issues Democrats are already plotting to pursue if they win control of Congress' vast arsenal of investigative powers — raising the stakes on the 2018 congressional midterm elections.