George Bush campaigned behind enemy lines on Thursday with a foray into Massachusetts, while Michael Dukakis charged the vice president with favoring $7 billion in new taxes and said, ``so much for iron-clad no-tax commitments.'' Dukakis, who will fly to Atlanta in 10 days to claim the Democratic presidential nomination, also said Bush had made a ``rather late commitment'' when he said Wednesday that he would name a Hispanic American to his Cabinet. Before leaving on a Western campaign swing, the Massachusetts governor added that he would select a running mate ``in the not too distant future,'' but did nothing else to clarify the reigning mystery of the presidential campaign. Bush, whose own nomination is set for the Republican National Convention in New Orleans next month, flew to Dukakis' political base of Boston. There he met with Bay State Republicans and spoke to leaders of the Greek Orthodox Church, which counts Dukakis among its followers. The vice president got a warm reception from the Greek group, which had heard a day earlier from Dukakis. Bush said it was just as well they didn't appear together. ``Too much charisma can be dangerous to your health,'' he said to laughter. The vice president met with President Reagan before leaving Washington, and the two men directed their aides to work closely to maximize Bush's chances of victory in the fall. Presidential spokesman Marlin Fitzwater also disclosed that Reagan may campaign on Bush's behalf in California when he vacations there this summer. California, the nation's largest state with 47 electoral votes, is Reagan's home. But Bush has fared poorly there in polls, and his aides are eager to cut into Dukakis' presumed lead in the state. Reagan is expected to campaign two days a week for Bush beginning in the fall, and Bush said Thursday the two would probably make some joint appearances. ``The president feels he can be especially helpful with conservative Republicans, Democrats and other key groups which are not registered Republicans, but which have voted for the Reagan-Bush ticket in '80 and '84,'' said Fitzwater. Reagan will be at his California ranch during the Democratic convention, but Bush said he himself may campaign during the first two days of the convention, hoping to ``get a little bit of ink'' in the news media during Dukakis' big week. In addition to his trip to Massachusetts, Bush dispatched New Hampshire Gov. John Sununu to Washington for a news conference designed to tar Dukakis. Sununu said tens of thousands of ``refugees'' are fleeing Massachusetts and Dukakis' administration each year and moving to New Hampshire. ``If Michael Dukakis fulfills his promise to do for the rest of the nation what he did for Massachusetts, then we are in serious trouble,'' he said. Dukakis has seemed to lose the political momentum in recent weeks, and he sought to regain it with his charge that Bush had forsaken his pledge to oppose any type of tax increase. He said the vice president supports a provision in trade legislation that calls for $1 billion in taxes for job training programs and also supports recently signed catastrophic illness health-care legislation with $6 billion in new taxes. ``So much for iron-clad no-tax commitments,'' Dukakis said of the centerpiece of Bush's campaign. Bush, in Boston, replied by making reference to Dukakis' signing of a cigarette tax and his support for another tax measure. ``I'm against raising taxes, and I think recent events here in this state that I don't plan to go into demonstrate we have a different view on taxes,'' he said. The Bush campaign also quarreled with Dukakis' assertion about the trade legislation and the catastrophic illiness health-care legislation. ``He is dead wrong on both counts and he is trying to blow smoke into the room,'' said spokesman Mark Goodin. In his home state, Dukakis said he expected to conclude work by the middle of next week on legislation to wipe out a looming budget deficit for the 1988 fiscal year, and on a package of tax increases and spending cuts for next year. Dukakis has been criticized repeatedly by Bush for agreeing to a new cigarette tax and other measures as part of the budget plan, for a total of $250 million in additional taxes and fees. Dukakis also scoffed at Bush's pledge before a Hispanic group in Texas to name a Hispanic member to the Cabinet. ``It strikes me that this is a rather late commitment,'' said Dukakis, who made a similar pledge a year ago. ``I don't know where he has been for the last eight years.'' Later, in Dallas, Dukakis spoke before the same group Bush had addressed a day earlier, and again jabbed at Bush over the pledge to appoint a Hispanic member of the Cabinet. ``Some people think it's enough to wake up after eight years and then promise opportunity for one Hispanic. I want to stand with you and create opportunity for 20 million Hispanic citizens across the country,'' he said. Dukakis also resurrected the issue of Reagan's veto of plant-closing legislation, using it against Bush. ``The president opposes it, the vice president opposes it, I don't know why.'' He said workers deserved the 60-day notice the legislation would provide before a plant could be closed and said the issue represented ``the fundamental difference in what a Democratic administration would mean to this country.''