The failed GOP repeal attempt gave Democrats a chance to promote popular aspects of the law — including its ban on jacking up rates for patients with pre-existing medical conditions. (Photo: Shutterstock)

Andy Kim decided to run against House Republican Tom MacArthur last year as he watched TV coverage of GOP efforts to repeal Obamacare while waiting in a hospital room for news on his unborn son.

Kim was sparked by MacArthur's amendment that would have let insurers charge more for patients with pre-existing conditions and his central role in helping the repeal pass the House. An ultrasound had just shown that Kim's son was dramatically underweight, and he wondered “if my baby boy is going to have a problem for the rest of his life.”

“What I promised myself and my family that day was I was going to do everything I humanly can to hold Tom MacArthur for what he just did,” said Kim, a Democrat who's challenging the New Jersey Republican in the November election.