Andrew P. Miller, the front-runner for the Democratic nomination to the U.S. Senate in Virginia, offered yesterday to accept an important rules change sought by his seven opponents and said his position on two others is "negotiable."

A spokesman for the seven candidates, Stephen Fleming, immediately called the Miller statement "the kind of conditional surrender we have been expecting." However, Fleming added: "Miller will have to go a lot further than this if he wants to avoid a rules fight at the convention."

Miller said at a press conference that his offer to accept a rules change was made in an effort to steer the party away from "bickering and permit a return to the real issue, which is: Who would be our party's strongest candidate in the fall campaign?"

At this point, 10 days before the opening of the Democratic convention in Williamsburg, Miller's seven opponents apparently control a majority of the 2,797 delegates and therefore believe they can win any rules fight on the floor. Miller said he expects to get more than 1,200 votes on the first ballot, but that would fall almost 200 short of a mojority.

The rules change the Miller agreed to yesterday would delete the requirement that any candidate who receives less than 5 percent of the vote on the first convention ballot drop out of the race.

Miller's opponents also object to rules that would eliminate the candidate receiving the least votes after each ballot and would permit the nominee to be chosen by a majority of the delegates voting, rather than a majority of the total delegates authorized for the convention.

"The bottom-person-out and majority rules are just as important to us as the 5 percent rule," Fleming said. "We want an open convention."

The Democratic convention rules were adopted in March by a temporary rules committee and can be ratified or altered by a permanent rules committee that will be chosen when the convention opens June 9. The permanent rules are subject to a vote of the full convention.

Changing the bottom-person-out rule appears to be the most important objective of Miller's opponents. The elimination of candidates on early ballots would increase Miller's chances of closing the gap between his delegate support and the majority needed to win the nomination.

Miller's opponents hope that by keeping all candidates alive through the early ballots they can demonstrate that Miller does not have the strength to put together a majority. If this happens, the opponents hope some Miller delegates will look for a compromise nominee.

Miller is considered likely to get more first ballot votes than the next two or three of his opponents combined. Trailing him in order of risk ballot commitments are State Sen. Clive L. DuVal of Fairfax County Norfolk City Council member G. Conoly Phillips, former Fairfax supervisor Rufus Phillips, former state Del Carrington Williams of Fairfax, State Sen. Hunter B. Andrews of Hampton former Fairfax supervisor Frederick Babson and Falls Church feminis Flora Crater.

Convention delegates were elected at city and county mass meetings on April 15 either as committed to a specific candidate or uncommitted. Those who are committed to a candidate will be free to vote for other candidates after the first ballot.

Miller said his opponents are seeking the Senate seat being vacated by Republican William L. Scott, who is retiring. The Republicans are scheduled to choose their nominee in Richmond on June 3.