Boston — If Massachusetts goes Democratic in the November presidential election, much of the credit might go to Geraldine Ferraro. The party's vice-presidential nominee, whose popularity in Bay State voter samplings has been greater than that of presidential candidate Walter Mondale, appears to have come through her latest campaign visit here with flying colors.
There is no immediate way to measure how much grass-roots the Ferraro appearance at a Sept. 26 noontime rally in Boston's Government Center may have won for the Mondale-Ferraro ticket. But it helped demonstrate a spirit of togetherness among Massachusetts Democratic activists.
Sharing the platform with the congresswoman from New York were most of the state's Democratic heavyweights, including US Sen. Edward M. Kennedy, Gov. Michael S. Dukakis, Boston Mayor Raymond L. Flynn, and Lt. Gov. John F. Kerry, the party's nominee for the US Senate.
The Ferraro appearance was particularly important to Mr. Kerry since it afforded him not only a few minutes to showcase his candidacy for the seat being vacated by fellow Democrat Paul E. Tsongas, but a public endorsement by his party's vice-presidential nominee.
Vice-President George Bush six days earlier had stopped off briefly in Boston to voice his support and that of President Reagan for Raymond Shamie, the Bay State's Republican senatorial nominee. The Bush boost came at a considerably smaller political pep session at a restaurant in heavily Italian-American, and largely Democratic, East Boston.
Mr. Shamie, a political conservative like the President, is counting on a visit to the Bay State by Ronald Reagan at some point in the campaign. Thus far, however, it is uncertain when such a visit might be, although Mr. Reagan, who carried heavily-Democratic Massachusetts in 1980, is known to be anxious not only to take the state's 13 electoral votes again, but also to pick up a US Senate seat on the home turf of Senator Kennedy.
Similarly uncertain is when, and how much, campaigning Mr. Mondale might be planning in Massachusetts during the remaining 51/2 weeks.
Of particular concern to state Democratic strategists has been the depth of Mondale strength among blue-collar residents, who once were considered sure Democratic voters. The strength of the state's economy and high employment, it is felt, might lead that group to stick with the present White House incumbent.
Being a woman and of Italian ancestry, Ms. Ferraro is being counted on to considerably boost the Democratic presidential prospects here.
Bay State Democratic leaders, not all of whom were on the Mondale bandwagon during the presidential primary campaign last March, view Ms. Ferraro as an especially effective campaigner.
The Democratic nominee for vice-president - whose campaign manager is John Sasso, now on leave from his post of chief secretary to Governor Dukakis - took full advantage of the Boston rally to touch political bases with a broad cross section of the electorate through her hard-hitting attack on the Reagan administration's performance.
Senator Kennedy, alluding to polls that show Reagan leading in Massachusetts, noted that ''when the Boston Celtics were in the playoffs and were behind, they came on to win the championship.''