Voters in Massachusetts and 10 other states will cast ballots today in the single most politically lucrative day of the presidential nominating process.

Democratic and Republican candidates raced around the South yesterday in one last round of intra-party squabbling, with Arkansas Gov. Bill Clinton, the Democratic front-runner, under attack and with President Bush predicting a sweep of GOP Super Tuesday contests.

In Massachusetts, former California Gov. Edmund G. Brown Jr. spoke at a rally on the Boston Common, while Vice President Dan Quayle addressed Republican supporters at Quincy Market.

Florida, the only Southern state where Clinton faces strong competition from former Massachusetts Sen. Paul E. Tsongas, was the site of much of today's bickering. Calling it "kinder, gentler voodoo economics," Tsongas criticized Clinton's proposal for tax breaks which include a middle-class tax cut.

Clinton, meanwhile portrayed Tsongas as having "a big advantage" in the Florida race, citing the amount of time the Lowell, Mass. native had spent there. Butdirecting his message to the large elderlypopulation of the state, Clinton said he was thebetter choice for the state.

"I've got by far a better program for tourism,I've got a better program for senior citizens, amuch better program for control of health carecosts," Clinton said.

The candidates gloves were off on television aswell. A Clinton ad alleged that Tsongas favors acut in cost of living adjustments for the elderly.

Tsongas, responding with his own as, said hisrecord on Social Security benefits was beingdistorted by Clinton. Yet Tsongas' campaignposition paper, A Call to Economic Arms, doesrecommend curtailing cost of living increases.

Brown, in a Rhode Island appearance, attackedClinton, calling him "not electable." He wasapparently referring to a Sunday New York Timesarticle that linked Clinton with the owner of afailed savings and loan. Earlier in the campaign,questions were raised about Clinton's maritalfidelity and draft record.

"You can't elect a candidate with a scandal aweek," Brown said. "I'll tell you that."

Brown faces his own difficulties on SuperTuesday, with little chance of winning any state.But the candidate hopes to erode some of Clinton'sand Tsongas support in the North, whereMassachusetts, Rhode Island and Delaware residentswill record their votes.

In all, 783 Democratic delegates and 421Republican delegates will be determined in today'sprimaries and caucuses.

Harkin Already Out

Even Iowa Sen. Tom Harkin, who dropped out ofthe race Sunday, hit the campaign trail yesterday,promising to keep fighting for his beliefs.

All three remaining Democrats said they wouldgo after Harkin's political base, which includesmany union workers. That group will carry muchweight in next week's Illinois and Michiganprimaries.

Harkin said he would "bear any burden" to helpa Democrat beat Bush in November.