Republican recruitment has been below par, probably because everyone hates the NRSC, McConnell, and/or Rick Scott, but no, Democrats do not have a realistic chance at holding the Senate unless something else changes.
And on the flip side, if things continue on a Republican trajectory the battleground may shift to NH/CT/WA. We could just as easily be talking about how lucky the Republicans are to have solid candidates in those races. (They blew Oregon and potentially Colorado, though.)
A republican is not winning the CT senate race especially with Stefanowski at the top of the ticket.
