But the politics are perfectly sensible in comparison to the policy involved. The ostensible purpose of including a repeal of the Affordable Care Act’s individual mandate in the Senate tax bill is to provide more room for middle class tax cuts. But if that’s really the goal, Republicans have a funny way of showing it. Yes, their latest proposal reduces slightly the tax rates — though only for couples who make more than $77,400 a year, and with the largest reduction for those making at least $120,000. And it increases the child tax credit slightly more than the original Senate bill, but the way the legislation is written excludes poor families from some of the benefit. It does, however, help out those who earn up to $1 million a year. But those middle class tax benefits, such as they are, expire after 2025. The corporate tax cuts, those are forever. Sen. Ron Johnson, a Wisconsin Republican, made waves Wednesday by pointing out the obvious tilt of the legislation and saying he would not vote for it without significant changes.