Saying their patience is at an end, conservative activist groups backed by the billionaire Koch brothers and other powerful interests on the right are mobilizing to pressure Republicans to fulfill their promise to swiftly  repeal the Affordable Care Act. Their message is blunt and unforgiving, with the goal of reawakening some of the most extensive conservative grass-roots networks in the country. It is a reminder that even as Republicans control both the White House and Congress for the first time in a decade, the party’s activist wing remains restless and will not go along passively for the sake of party unity.