It is early afternoon in the crowded rotunda, and the seven women in white sit listlessly under the great dome. They are pale and drawn. They haven't eaten in 23 days.

The fast is part of one of the most emotional lobbying efforts ever put together in behalf of the Equal Rights Amendment. In a last-ditch effort to ratify the amendment before the June 30 deadline, ERA supporters have marched by the thousands on Springfield, mounted a $300,000 television advertising campaign, chained themselves outside the state senate, unfurled a giant American flag in the senate chambers, and picketed the mansion of Gov. James Thompson.

Despite all this activity, even the ERA's most adamant supporters concede that they lack the votes to approve the amendment. Thompson, who has been accused of being a lukewarm ERA supporter, insists it all has been counterproductive.

"The chainers [15 women who chained themselves to a railing for four days] haven't helped, the fasters haven't helped, the marchers haven't helped, the picketers haven't helped," says Thompson, locked in a tough reelection campaign against former Sen. Adlai E. Stevenson III.

The most visible action has been an announcement by state Sen. Forest D. Etheredge, a Republican ERA supporter, that he will not vote for the amendment until the fast ends.

The legislative situation here is complex. ERA supporters claim the amendment has majority support in both the state house and senate. But the 1971 state constitution requires that amendments must pass with a three-fifths majority.

A federal judge, however, has found that the legislature can change that rule. So the fight here is centering on changing the rule.

That fight was dealt a blow last night, however, when House Speaker George Ryan, an ERA opponent, ruled that the change was not germaine as an amendment to another rules measure working its way through the House. His ruling was upheld by the House 97 to 4, with most ERA backers refusing to vote. Separate legislation is pending before the House Rules Committee, but there is no indication when and if it will reach the floor.

State Sen. Dawn Clark Netsch, a longtime ERA supporter, said ERA forces had built up a momentum which she thought had brought them "up to the brink" of passing the amendment until last week when Etheredge made his announcement.

"We were clearly set back, and I'm not sure if we can put it together again," says Netsch.

The battle has created a delicate political situation, with Thompson, a Republican, clearly on the defensive. He has been a longtime ERA supporter, but his running mate for re-election, House Speaker Ryan, opposes the amendment and ERA forces claim the governor has dragged his feet lobbying for it.

Thompson has taken conflicting positions on the rule change. In his most recent public statement Tuesday, he straddled the issue, saying only "the rules of ratification are for the body to determine, as our constitution and the federal court have made clear."

Ryan is more blunt. When he was asked about thousands of ERA supporters who marched in Springfield Sunday, he said, "Why should I want to watch those idiots."

Thompson reprimanded Ryan for that remark. But in an interview Ryan said, "The ERA has been turned into a political football to bang Thompson and Ryan with. They're just trying to make us into scapegoats."

Each day since May 18, the seven fasters, dressed in white with purple sashes, have gathered for three hours in the Capitol rotunda.

Sonia Johnson, who was excommunicated from the Mormon Church in 1979 for her support of the ERA, is by far the weakest of the group. Her lips are pale, her eyes sunken in their sockets. On Monday, she was woozy, unable to hold up her head as she sat in her wheelchair.

She became dizzy and was placed, almost unconscious, on a blanket on the marble floor. Eventually, she was taken to a hospital. She was released after doctors diagnosed low blood pressure.

A few yards away, beside a bronze statue given the state by the women of Illinois, was another group of women. Periodically, these women ate candy bars in front of the fasters. One proudly displayed a large sign, which read:

"Are you for ERA? Evil, Rebellious, Agitators. The communists, lesbians and homosexuals and those who wish to destroy America and the right to be a true wife and homebuilder are for the ERA."

Scores of tourists and state workers on lunch break crowded around.

"I don't think any human being should sacrifice her life for another woman," said Jo Lammert, a middle-aged state worker standing near the women in the rotunda. "I'm not worth it. I don't think any woman is."

The fasters clearly don't see it that way. They all are deeply religious women, brought together by their deep commitment to equality for women.

"We all felt a religious and spiritual calling to be here," said Mary Ann Beall of Falls Church.