There should be an indpendent Russian probe, which there now is. Until Mueller makes a recommendation, there is nothing else to talk about.
What Dems should be talking about is the House healthcare bill and Zinke shrinking National Monuments. They could talk about Trump's Muslim ban, which gets shot down in every court it goes to. They could talk about potentially disastrous foreign policy decision of selling weapons to the Saudi's, a fundamentalist Muslim dictatorship. There are easy targets out there, but b/c the Clinton-wing of the party still can't get over the loss (that they blame on Russian and Comey), those topics remain their talking points.