National Democratic groups have begun to target a Tennessee race rocked by revelations that the Republican incumbent, a doctor, once discussed abortion with a patient who was his mistress. The House Majority PAC, the campaign committee associated with House Democratic leaders, on Friday announced it is spending $100,000 on TV ads criticizing Rep. Scott DesJarlais. Meanwhile, the Democratic Congressional Campaign Committee has added DesJarlais’ challenger, state Sen. Eric Stewart, to its “Red to Blue” list of 55 candidates to receive campaign cash, though it didn’t say how much. DesJarlais, a physician from southeastern Tennessee, doesn’t dispute the contents of a transcript of the recorded conversation, but says he used stark language to push the woman to admit she wasn’t pregnant. He claims there was no pregnancy and no abortion.