Sen. Lindsay Graham’s proposal for a nationwide ban on abortions is not just a political disaster for Republicans, it’s bad policy for the nation.

The South Carolina senator is asking the Democratic-controlled Senate to vote on a bill that would outlaw abortion in every state after 15 weeks into the pregnancy, with exceptions for rape, incest and the life of the mother.

It obviously won’t pass. But it does give Democrats another hammer with which to hit Republican Senate candidates in the midterm elections.

Democrats are already spending the largest amount of their money — $124 million so far — on warning voters that Republicans, if they retake the Senate this fall, will do exactly what Graham is proposing.

Graham’s aim is to put Democrats on record voting against what he sees as a reasonable regulation of abortion. But Democrats aren’t afraid of doing so. A majority of the electorate supports keeping abortion legal. It’s Republican candidates who are walking a tight line on the abortion issue, and most would rather not have the question dominate the campaign conversation.

Graham’s proposal makes it nearly impossible for those Republicans to keep the focus on issues such as inflation, failing schools and rising crime.

Aside from the political blunder, Graham’s proposal flies in the face of the argument Republicans have pressed for decades, that abortion regulation is a state’s rights issue and not under the realm of federal authority.

This summer’s Supreme Court ruling overturning Roe v. Wade gave a boost to that contention.

The court returned abortion lawmaking to the states. And that’s where it belongs.

Graham said last week he doesn’t see abortion as a states’ rights issue, but as one of human rights.

Even if he’s right, it doesn’t give Congress a green light to charge in and attempt to impose a national standard.

As the court said, state legislatures and ballot boxes are the correct venues for making abortion law. Voters in Michigan and several other states will vote in the upcoming election on ballot proposals that will decide the matter. Some states will adopt more restrictive measures, and some will loosen abortion access. That’s precisely the scenario the court envisioned.

The decisions of voters hopefully will reflect the values and will of the people of those states.

Graham’s initiative would again make abortion a federal matter and continue the bitter and divisive battle that has raged since Roe was decided in 1973.

In most states, voters will assure, one way or another, that abortion remains legal.

Graham’s proposal — a ban after 15 weeks with some exceptions — could serve as a model for state Legislatures who are honestly attempting to craft laws to appease the maximum number of their citizens. Polls show strong support for keeping abortion legal in the first trimester, but it falls off for later-term abortions.

Graham should be encouraging state lawmakers to adopt his standard, including those in Michigan, which is hurtling toward passage of a much more permissive ballot measure that could shield abortion from all but the barest regulations.

That’s where resolution of the issue should remain — with the states.