On the morning after he proposed a $250 million-a-year tax increase that some Maryland politicians regarded as an act of electoral suicide, Attorney General and gubernatorial candidate Stephen H. Sachs said he woke up today "feeling pretty good about myself."

His wife Sheila had a different view, however, of Sachs' proposal to increase the sales tax by 1 cent to pay for a major increase in education aid. When she heard about it, Sachs recounted, "She said to me, with her eyes rolling, 'You've been right more often than I have in the past, but I don't know about this one.' "

One hundred and sixty-two days from now, when the votes are tallied in the Democratic primary between Sachs and Baltimore Mayor William Donald Schaefer, Sachs' proposal will be viewed in its proper context: either as a bold stroke that turned his gubernatorial campaign around, or as the height of political folly.

Some state legislators interviewed here, including some Sachs supporters, described the sales tax proposal as politically foolhardy and fiscally imprudent, given the state's robust economy.

And some said it was either an attempt to breathe life into a campaign that surveys indicate was making only modest gains on Schaefer's wide lead or a strategem dictated by a teachers' and educational lobby that makes up one of Sachs' most loyal constituencies.

But by Sachs' account, the education plan and tax increase was anything but ill-considered. He said it dated to discussions that began last fall.

"We decided then that the political risks were necessary in order to advocate a program that would make a difference," Sachs said. The teachers' lobby had nothing to do with it, he added.

If there was an immediate positive side to Sachs' announcement Monday, it came in the form of a large dose of publicity that his campaign sorely needs. A potential long-term benefit may be the shaping of gubernatorial debate around what Sachs describes as Schaefer's vulnerability for having ignored social concerns in favor of business development.

Sachs himself saw an immediate psychological boost to his campaign, for he is far enough behind Schaefer in the polls to attempt the kind of unfettered debate that might not be possible if the race were closer.

"I have the political luxury of being able to tell the truth," he said. "I don't need to do that kind of careful, cautious analysis. There is a freedom about that."

During the next five months, Sachs' problem will be in keeping the offensive going on education and avoiding the defense on raising taxes.

Though Sachs said today that the two issues "are inseparable," some legislators in Annapolis were remembering Walter Mondale's disastrous call for a tax increase in the 1984 presidential campaign.

The wriest comparison to Mondale came from Del. Gerard F. Devlin (D-Prince George's). "The only thing left for Sachs to do," Devlin declared, "is to choose an Italian woman for a running mate. Too bad (Del.) Connie Morella is a Republican."

Even Sheila Sachs was reminded of Mondale, the attorney general acknowledged:

"Last week she said -- I think affectionately -- 'So you think you'd rather be right than be president?' "