Democrats in this state have stepped up their charges that the Republican Party intimidated minority voters in last Tuesday's gubernatorial election, the results of which were so close that the winner still is not certain.

Neither Republican Thomas H. Kean nor Democrat James J. Florio has hinted that there was any fraud, but Florio--who trails Kean by 1,947 votes--maintains that intimidation kept some minority voters away from the polls.

Republicans contend they used legitimate means to combat a tradition of urban vote fraud in the state.

On Friday, three prominent Democrats held a press conference to denounce the National Ballot Security Task Force as a deliberate Republican effort to scare away minority voters.

The mysterious group--which appeared suddenly on election day in heavily black and Democratic precincts of Newark, Camden and Trenton--was later acknowledged to be a creation of Commitment '81, a joint $1 million venture of the GOP state and national committees.

Rep. Peter W. Rodino (D-N.J.), Newark Mayor Kenneth Gibson and State Civil Service Commissioner S. Howard Woodson argued that the "task force" was reminiscent of efforts to deprive blacks of voting rights in the Deep South. The task force, which appeared in about 75 precincts, put up four-foot-high posters warning that fraudulent voters could be arrested.

A toll-free telephone number was listed and a $1,000 reward offered to anyone with information that could lead to such arrests. In at least a few precincts, the Democrats charged, the task force fielded armed, off-duty police officers wearing its armbands.

The Democrats went to court immediately. At 4 p.m. on election day a judge in Trenton issued a statewide order enjoining use of the signs, which he said violated state law by failing to say who paid for them.

Woodson said he called directory assistance to check the toll-free number on the posters and was told it was listed as the Republican National Committee.

"We are delighted to be a partner with the Republican Party in New Jersey in their ballot-security program to ensure an honest election," GOP national chairman Richard Richards responded.

"Anyone opposed to ballot security obviously must be supportive of election fraud," he said.

In Washington, meanwhile, Democratic National Committee officials said they have contacted Drew Days, who headed the Justice Department's civil rights division in the Carter administration and who now teaches at Yale law school, for help in determining whether there might have been a civil rights violation.

DNC spokesman Bob Neuman said the party viewed the New Jersey actions as "a very serious matter" and was investigating reports that other Republican-affiliated groups had pursued similar tactics in Virginia and other states.

The New Jersey GOP released a statement claiming a Kean victory and asserting: "We are not overly surprised that the Democratic Party has developed trumped-up charges in hopes they can challenge the result."

Carl Golden, Kean's press secretary, said the GOP candidate would be upset if Republican workers had intimidated any voters.

However, Golden defended the use of the "security force" in many precincts that "have not seen a Republican poll watcher or challenger in 20 years."

Woodson announced the formation of a new organization--"Right to Vote '81"--that is collecting affidavits from voters who claim to have been intimidated. He declined to reveal how many affidavits have been collected or to describe their contents, saying that the information will be turned over to the state attorney general's office.

Rodino, chairman of the House Judiciary Committee, suggested that charges of intimidation may threaten the validity of the election. But Woodson said "this has nothing to do with election results."

Meanwhile, the status of "emergency" ballots in predominantly Democratic precints of Essex County (Newark) still awaits a decision by the state Supreme Court.

A lower court judge ruled Friday that the ballots could be counted even though there "appears to be some irregularity and some prejudice." But a Supreme Court justice stayed the ruling at the request of the Kean campaign, which argued that the ballots were delivered to the county clerk's office too late to be considered valid.