The two Democratic contenders for their party's Virginia gubernatorial nomination unleashed their toughest and bitterest attacks yet against each other last night at a debate in Fairfax County. It was their last formal confrontation before Saturday's crucial statewide delegate selection caucuses.

Lt. Gov. Richard J. Davis and Attorney General Gerald L. Baliles verbally pounded each other on the abortion issue, repeatedly returning to the subject despite admonishments from the moderator. Each candidate also accused the other of purposely distorting records.

Both campaigns acknowledged that debates between the two have become increasingly acrimonious despite early campaign pledges to avoid divisiveness.

"The focus is a little sharper," assessed Baliles after last night's 80-minute debate before an audience of about 100 at Lee High School in Franconia.

Davis campaign aide Tom King termed the increasing hostility "a natural phenomenon."

The two faced off in one of the most coveted delegate strongholds in the state. Caucuses in Fairfax County on Saturday will select 388 delegates to attend the state convention in Richmond in June that will choose a nominee to succeed Democratic Gov. Charles S. Robb, who under state law cannot succeed himself.

Baliles, declaring that he is "prochoice" on the abortion issue, accused Davis of hiding "behind a cloud of smoke and . . . ambiguity."

Davis said he believes women should make their own choices in the matter of abortion, but said if he had been governor, he would have signed either version of a controversial measure killed by the General Assembly this year that would have required minors to obtain parental or judicial consent before obtaining an abortion.

Davis launched the debate with an opening statement alleging that Baliles has only recently espoused strong support of the Equal Rights Amendment and suggesting that Baliles is weak on the issues of human rights, partially because he has established no civil rights division in the state attorney general's office.

"I've been committed to the ERA for a long time and you know it," shot back Baliles, explaining that even though some of his votes as a state legislator may have had the appearance of being against the amendment, they actually were intended to oppose some of the legislative parliamentary procedures being used in the ERA debate.

The National Rifle Association's endorsement of Baliles also sparked friction between the two. Davis, taking a sarcastic shot at Baliles for the endorsement, provoked Baliles to note that Davis' campaign had actively sought the NRA endorsement this year and in past campaigns.