The Virginia House today declared former Alexandria legislator James M. (Big Jim) Thomson to be the newest member of the state's powerful regulatory commission.

No, he's not, came the simultaneous word from the Senate.

With that, the General Assembly plunged into a drawn-out constitutional and parliamentary quandary that made a shambles of tight committee schedules at the hectic midpoint of the 1985 session.

"There have been wars fought over principle," said state Sen. William F. Parkerson Jr. (D-Henrico) after the Senate refused to go along with the appointment of Thomson, now the state's insurance commissioner.

The Senate, fueled by its differences with the House as well as personality clashes among the Senate members themselves, voted to support former Richmond legislator Edward E. Lane.

Lane, who also served in the House, has the support of several senators who remember Thomson's zeal in lambasting the Senate when he was House majority leader before his election upset in 1977.

Thomson, once the most powerful Northern Virginia legislator, is credited with being a tough insurance commissioner. But he also has drawn fire from some insurance lobbyists, who oppose his appointment to the powerful State Corporation Commission, which oversees insurance as well as other corporate and utility decisions.

"It's night baseball -- with the lights out" now, said Sen. Joseph V. Gartlan Jr. (D-Fairfax).

He said that it's impossible to predict how the appointment will be resolved.

At issue is whether the Virginia Constitution requires that a nominee to the SCC be chosen by a majority vote of the combined 140-member General Assembly or whether there must be separate majority votes in both the 100-member House and 40-member Senate.

Lt. Gov. Richard J. Davis, who presides over the Senate, and House Speaker A.L. Philpott (D-Henry) huddled today in an attempt to reach a settlement, but failed.

The House, which then voted 86 to 12 for Thomson, insists that the votes in both chambers have to be combined, which would mean that Thomson needed only 71 votes to have a majority of the entire legislature.

"We had that script and didn't use it," said Parkerson after the Senate voted 26 to 13 for Lane.

Both chambers also are awaiting an advisory opinion from state Attorney General Gerald L. Baliles, a candidate for governor who is not eager to enter what is largely a political fray.

An opinion in 1971 by Attorney General Andrew P. Miller sided with the Senate position in a similar case, but the attorney general's opinions are not binding.

If Baliles agrees with Miller, it could mean the House might go to the state Supreme Court for a ruling. If the legislature adjourns Feb. 23 without reaching agreement, Gov. Charles S. Robb could make the appointment.

The issue was touched off more than a week ago when the House and Senate Democratic caucuses met to pick a candidate for the SCC and no one held a clear majority because of two disputed Senate votes.

State Sen. Dudley J. (Buzz) Emick Jr. (D-Botetourt), who cast one of the disputed votes and was against both Lane and Thomson, seized on the parliamentary confusion in hopes of forcing a new vote, perhaps for a compromise candidate. Emick, a Senate maverick, sat quietly at his desk much of the day, smiling at the confusion swirling through the Capitol.

The only winners so far in the dispute are the Republicans, outnumbered in both chambers, who rarely have a say in judicial appointments.

"The Democrats look very bad," said Gartlan.