As the movement to extend the deadline for ratification of the Equal Rights Amendment gains momentum, I keep hearing pro-ERA forces accused of "trying to change the rules in the middle of the game."

I am well aware that women are generally held up to the purest standards that can dance on the head of a pedestal. But this is ridiculous. The name of the ERA game is, after all, politics. These people are not trying to change the rules; they are trying to use them to win. Which is the point of the game.

The ERA was passed by Congress in 1972. There was nothing especially sacred about the seven-year limitation for state ratification. "Seven" was the number arrived at, not by tarot cards or the Constitution, but by custom and political compromise.

At the time, ERA supporters agreed to this figure despite the warnings of old hands like Alice Paul. They felt as hopeful as Martha Griffiths, who probably remembers every night before she goes to sleep that she once said, "Personally, I have no fears that this amendment will be ratified . . . as quickly as the 18-year-old vote."

Now, led by the National Organization of Women, they are trying the perfectly legal tactic of urging the Congress to extend the limit for seven more (and final) years. This extension is the prerogative of the Congress. It is well within the rule book known as the Constitution.

But what bothers me most about the whole "rules of the game" chatter is the sheer chutzpah of the chatterers. It is the ERA opponents who should be thrown into the penalty box.

While the pro-ERA forces have been playing chess, their opposite numbers have been playing rugby. It was the pros who behaved like good little Goo-Goos, targeting their candidates, signing nomination papers and getting the votes out - just like it says in government classes. If the fix hadn't been in, the ERA would have passed its last three states months ago.

In Nevada, 11 state legislators who were elected on pro-ERA platforms went sheepishly over to the other side at the first cry of "Red Rover." Eight of them (may their debts swell and block their gateway to paradise) accepted pro-ERA campaign contributions.

This charming athletic display was reenacted in Florida. There, the women voted out the anti-ERAs and voted in the pros, and then watched as the two pivotal "yes" votes turned into "no's."

The Illinois rematch, on the other hand, looked like something created by Dick Tuck from his bag of tricks. Twice the ERA gathered a majority vote in the state legislature. In any other state, that simple majority would have meant passage. But in Illinois, you need a three-fifths majority under the new state constitution although - excuse me while I break into hives - this rule is generally considered unconstitutional.

As Ellie Smeal, president of NOW, puts it: "We were ignored in the election process." Speak to me not of rule-rigging.

Only in the past year have the pro-ERA forces learned the effectiveness of end runs around politics. The "conventions boycott" in nonratified states has been deliciously successful. This vision of clout has done the amendment more good than all the "due process."

But we still are in a situation in which the "will of the majority" has been thwarted by a handful of legislators. A full two-thirds of the states have passed this amendment. A majority of people polled - including those in unratified states - are in favor of it. The younger population overwhelmingly supports it. Yet it is in great danger of failing.

Some crucial state legislatures won't even meet again to vote until after March 1979. Perhaps the most potent problem facing passage before the deadline is the deadline itself. During the Florida fight, buttons sprang up with the slogan "ERA Won't Go Away." The pro-ERA people were aware that the opposition tactic was to convince legislators that if they held firm one more time, the amendment would just disappear.

The ERA won't go away. But if it fails to meet the deadline, it could become part of the collective consciousness of women in this country. They would realize that they had experienced disappointment and betrayal precisely because they believed - not wisely but too well - in the game.

The pro-ERA people wouldn't be purists if they neglected to press for extension. They'd be pure fools.