Last week's Jefferson-Jackson dinner in the Virginia capital took on the appearance of an evening of prize fighting in which the speakers squared off against one aspect or another of the state Democratic Party.

The main event matched presidential aide Midge Costanza against the party's conservative establishment.

Some party leaders, including chairman Joe Fitzpatrick, had wanted to withdraw the invitation to Costanza at the last minute because she criticized Democratic House of Delegate leaders for opposing ratification of the Equal Rights Amendment.

In the end, it was Costanza's style of unrelenting, barbed humor rather than the substance of her speech that left some of the slightly stodgy Virginians wondering if the party was big enough for her and for them.

Before Costanza threw her political jabs at the old guard Democrats, Lt. Gov. Charles S. Robb put on a preliminary bout in which his opponent was anyone who would exacerbate the divisions in the state party.

Robb reminded his audience of 700 that if the Democrats lose this year's U.S. Senate race, it will mean a stretch of at least 13 years without electing a Democratic senator or governor in Virginia. Such a string of statewide losses, he warned, would encourage the Republican Party to make a more serious effort to whittle away at the huge Democratic majorities in the General Assembly.

Robb blamed party factionalism for this state of affairs.

"For far too long, we've had tunnel vision," he said. "We all agree our party ought to stand for something, but we've defined our objectives too narrowly. We want to see the party as a spitting image of ourselves and of our own views on every issue . . . We've got to be more tolerant. We've got to get rid of our purge mentality. We've got to concentrate on those broad, fundamental principles that unite us."

After proposing that a commission of elected officials and party officers come up with a plan to improve the state party organization, Robb came back to "fundamental principles."

"There's still only one party of the people, blind to color, blind to class, sensitive to human rights and responsive to human needs," he said. "And so as Democrats, Virginia Democrats, it is time to state our beliefs, to demonstrate the differences, not among ourselves, but between Republicans and Democrats."

If Robb is serious about stating the differences between Virginia Democrats and Virginia Republicans, he is setting his party on a novel course.

Neither party in recent Virginia history has seriously attempted to link itself to support of any policy course that actually is in controversy either in the Assembly or the executive branch of the state government.

As a result, there is no basis for determining any difference between the parties.

Yet, there is no lack of policy questions for the parties to tackle. The relationship between urban areas and the suburban and rural counties that surround them has plunged the Assembly into an endless controversy over annexation and revenue apportionment.

The pleas of local governments for more revenue raise fundamental questions of fair tax policy.

Persistent segregation in the college system raises questions of fundamental civil rights.

Abortion, parimutuel betting, rape, the proposed Equal Rights Amendment, conflicts of interest in a part-time Assembly - these and countless other issues seem unable to attract the interest of the two major political parties in the state.

The Democratic majorities in the House and Senate published a policy statement early in this Assembly session that was devoid of proposals to deal with important policy issues.

The Republican minority issued a telling lampoon of the Democratic non-policy statement, but failed to come up with any meaningful policy statement of its own.

The failure of the parties in the Assembly to take comprehensive policy stands is not offset by a policy-making group in either party organization and the program of the Republican governor, John N. Dalton, is so selective that it does not reveal any overall Republican policy plan.

In this vacuum, one can only wish Robb luck. If he succeeds in establishing meaningful differences between the two state parties on meaningful policy questions, the day may come when Virginians can take political parties seriously again.