Sweeping changes that congressional Republicans made to the Affordable Care Act and Medicaid are starting to take effect, fueling an election-year blame game over coverage losses.Why it matters: A rise in the uninsured rate will put more stress on the health system and ratchet up concerns about health costs in an election year where affordability is voters' biggest concern.Driving the news: The changes are hitting home, with about 1.2 million fe…