evidence: WASHINGTON — Donald Trump took aim at the Affordable Care Act on Tuesday in his presidential debate with Kamala Harris, reviving a 15-year-old partisan fight over a law that has swung from a liability to a political asset for Democrats. [...] Trump indicated that he’d only eliminate the ACA, also called "Obamacare," if he could devise a better and cheaper system. Pressed by debate moderators on whether he has a plan, he said, "I have concepts of a plan," adding that he intends to release "concepts and options ... in the not-too-distant future." [...] The 2010 law, signed by then-President Barack Obama, was unpopular early on and weaponized politically by Republicans, who vowed to "repeal and replace" it if given power. But in 2017, when Trump and a GOP-led Congress sought to undo the law, it sparked a public backlash and enhanced the ACA’s popularity. A Trump-backed Republican repeal bill sought to roll back the subsidies for expanding coverage and unwind some of the ACA’s protections for people with pre-existing conditions, one of its most popular features. It fell one vote short when Sen. John McCain, R-Ariz., unexpectedly voted "no" during a late-night Senate session.