Sometime in 1966 about the time his wife expressed amazement at his thinking, the light of dawn began to reach Sen. Birch Bayh (D-Ind).

What amazed the late Marvella Bayh was that her husband, who had just become chairman of the constitutional amendments subcommittee, could oppose the idea of direct election of presidents.

Bayh looked it over, gave it some thought and became a convert. From his forum as chairman of the Senate Judiciary subcommittee. He became the No. 1 champion of a constitutional amendment to abolish the electoral college and directly elect presidents and vice presidents.

Thirteen years have passed, Bayh is still the No. 1 champion of direct election and no issue has been debated more and remained still unresolved on the Senate calendar.

To get an idea of how the time has gone, consider this: while the debate on direct election has ebbed and flowed, Bayh's subcommittee has started four other constitutional amendments on their way to ratification by the states.

Two, the 18-year-old vote and presidential succession, have been ratified. Two others, the Equal Rights Amendment and District of Columbia congressional representation, remain pending.

But the Senate now appears to be closer than ever to a final vote on the direct-election amendment, although the outcome, by Bayh's estimate, is still very much up in the air.

A first order of business after the Senate returns from its recess this week will be Tuesday vote on Bayh's cloture petition, a move to cut off lengthy floor debate that went on intermittently last month.

If cloture is invoked and other possible amending tactics thwarted, a final vote on direct election could occur before week's end. Bayh said in an interview that he is fairly confident that he can round up the 60 votes needed to invoke cloture. But he is less certain about the 67 votes needed to pass the amendment.

"It is touch and go - about a dozen senators are undecided. Those dozen will decide it," he said.

Should the Senate adopt the amendment. House action would be required. Although the house has changed since then, direct election was approved 10 years ago by 339 to 70.

As the new Senate vote nears, Bayh and his allies plan a last-minute campaign to help the "undecideds" make up their minds. Allies include the American Bar Association, the AFL-CIO, the United Auto Workers, the League of Women Voters, Common Cause and others.

One of their arguments will touch on an irony of the years-long debate, that while many senators oppose direct election of presidents, opinion polls have consistently shown a majority of the public in favor.

In a recent followup to a survey of state legislators made in the 1960s, Bayh's subcommittee quizzed every member of 14 small-state legislatures, the presumed founts of opposition to the amendment.

A majority in each state favored direct election. Overall 61 percent of the respondents favored it, 24 percent opposed it and 15 percent were undecided.

Still another irony in the debate is that some doubters, although directly elected to the Senate themselves, see abolition of the electorial college as "ominous" and "radical," in the words of Sen. Daniel Patrick Moynihan (D-N.Y.)

Virtually everything that could be said and thought about direct election, pro and con, has been said and thought in the Senate since Bayh took up the matter in his subcommittee in 1966.

Proponents call it one of the most logical and democratic changes that needs to be made to the American system of government, eliminating the uncertainty of the electoral college, giving equal weight to every presidential vote, assuring that every president is in fact the people's choice.

Opponents led by Sens. Strom Thurmond (R-S.C.) and Orrin G. Hatch (R-Utah), call it the most important domestic issue facing the Senate, and ugly in its portent.

They argue that change would upset the political party balance, encourage fraud, increase the influence of the national media, remove the states from their important role in the electoral process.

Moynihan described the question this way: "In the guise of perfecting an alleged weakness in the Constitution, it in fact proposes the most radical transformation in our political system that has ever been considered."

Under the electoral college, with the winner of each state's majority getting the state's electoral votes, it is possible for a person to be elected president without a popular majority.

That occurred in 1888 - Grover Cleveland had more popular votes but lost the presidency in the electoral college to Benjamin Harrison. Other elections in the last two decades have raised similar possibilities, although they did not occur.

"We've been close to having electoral winners who were popular vote losers," Bayh said."There are those who say if the system isn't broken, don't fix it. That's like saying the house isn't on fire, so I don't need fire insurance."

For years, literally, Bayh has been saying the day will come when the electoral college throws the country into a crisis. He remebers a lesson.

Critics said the 25th Amendment, which Bayh got rolling, just wasn't necessary. Shortly after it was ratified, it was put to use. It provided the machinery for Gerald R. Ford's succession to Richard M. Nixon in the White House in 1974.

Bayh isn't saying "I told you so," but he could.