Complex sentence: By mid- 2012, Obamacare had become the most common colloquial term to refer to the law by both supporters and opponents, in contrast to the use of "Patient Protection and Affordable Care Act" or "Affordable Care Act" in more formal and official use.
Split into simpler sentences: By mid- 2012, Obamacare had become the most common colloquial term used to refer to the law by both supporters and opponents. In contrast, the use of "Patient Protection and Affordable Care Act" or "Affordable Care Act" became limited to more formal and official use.