Peggy Noonan should stick to ghost-writing speeches for presidents or anyone else who will use her considerable talents for such work. She should discard the notion that her famous ''read my lips -- no new taxes'' line for candidate George Bush qualifies her as a maker of policy.

Noonan has already gotten considerable mileage out of her stint as a speech-writer at the White House and for creating the ''read my lips'' phrase for Bush. All students of the 1988 campaign agree that phrase contributed enormously to his victory over Democrat Michael Dukakis.

She has written a book titled ''What I Saw at the Revolution: A Political Life in the Reagan Era,'' which stayed on The Post's best seller list for 11 weeks earlier this year.

Now in response to an invitation from the Republican National Committee, which met in Chicago last week, Noonan delivered a little lecture of her own ''about what Republicans are, and what we must be in the future -- not only in order to win but to lead wisely and justly.''

Noonan's advice to the party was that ''we must not lose the tax issue.'' She is unhappy to see her ''no new taxes'' phrase put in limbo -- although she's too subtle to say so directly. Rather she told the RNC: ''We cannot lose this issue for political reasons: If we become like the Democrats, we will suffer their fate.''

The Wall Street Journal liked Noonan's address so much that it printed a lengthy extract on the editorial page. It was her second appearance in six weeks in the space often reserved for heavyweights such as Milton Friedman, Herbert Stein and Peter Drucker. The headline: ''Keep the Republican Faith.''

Bush's suspension of the ''no new taxes'' pledge was born of an acknowledgment that without substantial new revenue, there is no way an exploding budget deficit can be contained. This came as a shock to professional Republican politicians such as Edward J. Rollins, co-chairman of the Republican National Congressional Committee.

In Rollins's view, Bush scrapped a tremendous political weapon. Rollins figures that giving up the ''no new taxes'' label could cost the Republicans 10 seats in the November congressional elections. In that assessment, Rollins may be right. So he and others such as Rep. Newt Gingrich (Ga.), the Republican House whip, are looking for an escape from Bush's new openness to a tax increase.

Noonan offered a possible scenario, based on a prayer that the Democrats will fail to come up with their part of the budget ''summit'' bargain -- an attack on the spending side of the ledger. Said strategist Noonan:

'' ... If the ideas offered are ultimately the same old bad ideas -- 'We'll spend, and you raise the taxes to support us' -- then it will be right and reasonable for the president to push away from the table and 'cut himself a walking stick.' That was Tolstoy's phrase when, at the age of more than 80, he walked out on an unhappy marriage after almost 50 years. He was endlessly patient -- just like a Republican. ...

''{In that case, Bush can} stand up, acknowledge what's happening, declare that an impasse has been reached and tell the Democrats: I'm taking it to the people.''

That caught the eye of The Wall Street Journal editors, who also don't like to fiddle with tax changes (unless you're talking about a reduction in capital gains taxes).

What Noonan is articulating, of course, is a hope that the budget summit talks will fail, restoring the tax issue to the Republicans, and to hell with the country.

But this GOP right-wing attack on Bush's withdrawal of his ill-advised no-new-taxes pledge is not the only one. What is equally disturbing is the potshotting against Bush by liberals who chastise him for ''lying to the American people.''

Some of this criticism comes from those who argued -- correctly -- that the ''no new taxes'' pledge had put the nation in a policy straitjacket, unable to fulfill its commitments at home or abroad. They can't have it both ways. If he was wrong in 1988 when he made the pledge -- and he was -- he's right now.

Bush's ''no new taxes'' pledge at the Republican convention was sheer demagoguery -- words crafted by Noonan on orders from Bush's campaign managers for the sake of politics, not for the sake of good government. Everybody knew it was a promise that eventually would have to be broken. But it served the political goal of helping get Bush elected.

Belatedly, Bush took the right step last month, agreeing to scrap the pledge in order to try to reach a deal with the Democrats to cut the deficit. He deserves praise for acting like a president now instead of a political hack.