Republican rival, Sen. Mark Kirk, is jumping on the fact that the trial will go forward.
Portman faces a tight race with former Gov. Ted Strickland.
The DSCC cards link vulnerable Senate Republicans to Trump's policy views.
The clip slams their opposition to confirming Obama's Supreme Court nominee.
The Texas Republican is up for reelection in 2018.
Ohio, Pennsylvania and Florida Senate races are all within the margin of error.
A hearing on a lawsuit against Duckworth is set for Thursday.
The ad said Feingold ignored a 2009 memo.
Democrats have targeted Kirk's seat as one they hope will help them retake the Senate.
Reid said Senate Republicans should "stop waffling" on Trump.