She’s also a savvy campaigner. In April she ran a remarkable ad featuring a woman recounting how Dr. Wehby had saved her from having to terminate her pregnancy and then saved her infant daughter’s life. The spot resonated particularly with women, of all political stripes. Some 57% of Oregon women voted for President Obama in 2012, and if Dr. Wehby pulls some of that group, Mr. Merkley is in a world of hurt. An early May poll had her leading by two points. Democrats are bitter at possibly having to divert campaign money away from more risky Senate races—Arkansas, Louisiana, Alaska—to a state they didn’t expect to be in play.

Thus the Democratic decision to portray an accomplished doctor as emotionally crazed and unhinged. The hope was to tank her primary bid, so that Mr. Merkley would face her more conservative and less electable GOP opponent.

Now that she’s won, Democrats will continue to pile on the “she’s-nuts” stories, as we’ve seen this week with a new piece about an Oregon woman who is being prosecuted for conning doctors (including Dr. Wehby) into doing unnecessary medical procedures on her eight adopted children. The goal is to rebrand Dr. Wehby as Glenn Close in “Fatal Attraction.” Imagine if the right tried this on Hillary Clinton.

Dr. Wehby can at least take solace that she’s not alone. Democrats have unleashed similar tactics in nearly every Senate race where they are vulnerable. In Arkansas, they are portraying Republican Tom Cotton as a greedy, heartless former McKinsey consultant. (The Romney redux.) In Michigan, they’ve labeled GOP candidate Terri Lynn Land a slum landlord. In Montana they are running an ad accusing Republican Steve Daines of being callous about rape victims. It features a woman saying she was raped at age 14, claiming Mr. Daines would make “criminals” of women who have abortions.