WASHINGTON — Senate Republicans suffered a dramatic failure early Friday in their bid to advance a scaled-back plan to overhaul the Affordable Care Act, throwing into question whether they can actually repeal the 2010 health law.Their latest effort to redraw the ACA failed after Sen. John McCain’s decision to side with a couple other Republicans against President Trump and GOP leaders. The Arizona Republican, diagnosed with brain cancer last week, returned to Washington Tuesday and delivered a stirring address calling for a bipartisan approach to overhauling the ACA, a process that may have compelled McCain to cast his rebellious vote.The vote was 49 to 51.Senate Majority Leader Mitch McConnell, R-Ky., had hoped to approve the new, narrower rewrite of the health law at some point Friday, after facing dozens amendments from Democrats. But the GOP defections left McConnell without a clear bill to push.McCain had been seeking an iron-clad guarantee from House Speaker Paul Ryan, R-Wis., that, if the Senate approved this latest proposal, the House would not move to quickly approve the bill in its current form and instead engage in a broad House-Senate negotiation for a broader rollback of the law. Ryan issued a statement intended to assuage the concerns of McCain and two others, Sens. Lindsey Graham, R-S.C., and Ron Johnson, Wis., but the 2008 presidential nominee deemed the speaker’s statement as insufficient.The standoff between the two chambers highlighted the extent to which Republicans have still not reached a consensus on how to rewrite President Barack Obama’s 2010 health-care law, and the degree to which Republicans are repeating many of the same back-room maneuvers that Democrats used seven years ago to approve the ACA.