Former Bay State governor's reelection bid -- repeat of 1978?

Massachusetts Democrats may be taking a second look at former Gov. Michael S. Dukakis.

Four years ago, they denied him renomination. But now, the comeback-bent Mr. Dukakis has gained what could be a major push to his 1982 reelection hopes -- the gubernatorial endorsement of the state's nonbinding Democratic convention.

In polling 68 percent of the nearly 2,200 delegate votes, Dukakis bested incumbent Gov. Edward J. King by a little more than 2 to 1.

But with the Sept. 14 Democratic primary still 31/2 months away, most Bay State political observers anticipate a lot closer battle than either the convention tally or recent public opinion samplings would indicate.

At this point in the 1978 campaign, for example, former Governor Dukakis held a similar wide lead over his chief challenger, Mr. King. That narrowed considerably, however, during the summer and had all but disappeared the week before the primary.

Recalling that experience, the current governor and his aides appear undiscouraged. They note that the lion's share of delegates to the recent party convention were liberals and moderates, chosen at party caucuses dominated by Dukakis supporters.

Those in the Dukakis camp, too, have not forgotten what happened to their candidate four years ago and are anything but overconfident.

In his campaign, the former governor is charging that his successor, despite his political party registration, is really a Republican, noting King's friendly relationship with President Reagan.

In the opinion of some King aides, that relationship cost the governor Democratic primary votes. But the governor has made it clear he has no intention of moving away from the President, as some of his political advisers have urged him to do.

The King campaign strategy is to portray his predecessor as ''a taxer'' and ''a spender.'' Close to $200,000 was spent in radio and television spots earlier this spring, focusing on tax increases that occurred during the Dukakis regime and claiming that taxes have declined since Mr. King became governor.

Dukakis prospects for regaining the commonwealth's executive reins were considerably enhanced in late April when Lt. Gov. Thomas P. O'Neill III abandoned his candidacy for the Democratic gubernatorial nomination.

Although the latter has not indicated which, if either, contender he will support, a majority of his supporters are expected to side with Dukakis.

If he wins the nomination, Dukakis could face John R. Lakian, a conservative Republican, on the November ballot. The latter, a multimillionaire and political newcomer, won the GOP endorsement earlier this year.

Mr. Lakian, however, will have two challengers -- State Rep. Andrew H. Card Jr. and former Boston City Councillor John W. Sears -- in the Sept. 14 Republican primary.