Ruth Hinerfeld gets up in the middle of the night a lot lately, and does a very sensible thing. She worries.

You see, Ruth Hinerfeld is head of the League of Women Voters. And right now, the Anderson Factor hinges on the League of Women Voters Factor.

The outcome of the 1980 presidential campaign may depend on whether or not the league invites independent candidate Anderson to join the two-party debates on television. In turn, the whole future of the two-party system may depend on the outcome of the campaign.

So, in the middle of the night, she worries because "the decisions we have to make do confront us with a rather awesome responsibility." The heat is on or, as Hinerfeld says in her careful league-ish way, "It is rather warm."

She sees something amusingly wry in all this. "The founders of the league adored controversy. We came out of the suffrage movement 60 years ago. We were formed in protest against the powerlessness of women.

"They would have been most gratified that we are in a situation right now where our decision is being awaited breathlessly by the men in power and the power brokers. I'm sure they are just chuckling in their graves."

What the men in power and power brokers are awaiting breathlessly this week is The List. On June 26, the candidates will find out the names of the advisory committee members who will draft the criteria or "eligible" debaters.

Sometime during July that advisory committee will submit its views to the board of trustees of the league's Education Fund. And by the end of the summer, the trustees will send out the most exclusive invitations in the country.

The debate over the debate is being cast publicly in terms of politics rather than principle. At this point, Carter wants Anderson out of the picture. Reagan apparently wants him in. The two heads of the advisory committee -- Republican Anne Armstrong and Democrat Newton Minow -- are not unaware of party loyalties.

Already the rumor among the Republicans is that the committee is stacked with Carter people, and the rumor among the Carter people is that the league trustees come out of tweedy suburban Andersonville. But there are two good reasons to expect the league to stay reasonably partisan-proof: their membership and their tradition.

There is no composite profile of a league member, but they tend to be between 30 and 50, married with two children and living in towns and suburbs of less than 50,000 population. More to the point, they are 117,000 issue-oriented and reform-minded women (and a few men) who boasted 20 years ago that their paper work weighed more than 3.5 tons.

They are likely to turn out two tons more on the subject of who should and shouldn't be eligible for the great debates.

But their allegiance has always been to the voters and the process, not the parties. This year, a large number of the voters are depressed, if not disgusted, by the choices dredged up by the "two great parties." They want at least a chance to vote for somebody else.

At the moment, Anderson has the advantage of being "somebody else." The latest polls show that if voters thought he could win, this relatively unknown independent would be running neck and neck with Carter and Reagan. This is not the stuff of fringe or freak candidacy. The voters should be able to see how Anderson measures up to the party men.

Sixty years ago, at the founding convention, the Mother of Us All, Carrie Chapman Catt, admonished: "If we are going to trail behind the Democratic and Republican parties . . . we might as well quit before we begin. If the League of Women Voters hasn't the vision to see what is coming and what ought to come, and be five years ahead of the political parties, I doubt if it is worth the trouble to go on."

Her words are right on target for 1980. There is nothing sacred about the two-party system. For 60 years, the league has worried much more about alienation from process than reform. This is a perfect moment and they are the perfect people to "see what is coming" and to push for "what ought to come."