It was a two-tier Redskins party yesterday at the McLean home of conservative activist Richard A. Viguerie. There was pate and salmon in the formal dining room upstairs while hot dogs and popcorn were being offered in the family room below.

The politics were two-tier, too.

Officially, Viguerie and the crowd of about 100 mostly conservative Virginia Republicans were there promoting his new Campaign for Virginia political action committee, which he hopes will raise $400,000 for Republican General Assembly candidates in 1985.

But on both levels of his house, Viguerie, who is renowned for his use of direct mail to raise millions for conservative causes, also was pursuing his plan to seek the Republican nomination for lieutenant governor of Virginia next year.

Viguerie, who never has been active in state politics and who surprised Virginia Republicans in early December by announcing his interest in the post, said yesterday he will formally announce before Jan. 20.

Three other candidates already have announced, including former Republican attorney general J. Marshall Coleman of McLean, who was the party's unsuccessful candidate for governor in 1981. He was not at the party.

Republican state Sen. John H. Chichester of Fredericksburg and state Del. A. R. "Pete" Geisen of Augusta County, who also are candidates for lieutenant governor, put in appearances at the party at which about $7,000 was raised.

"All we need is Marshall and we could each give five-minute speeches, take a vote and we could all stay home for the next five months," Viguerie joked during a welcoming speech at halftime of the Redskins-Chicago Bears game.

GOP nominees for governor, lieutenant governor and attorney general will be chosen at a state convention in Norfolk May 31.

"I think its kind of late for any more candidates to announce ," said former Republican state senator Eva Scott of Amelia County. "So many people have already committed." Scott, a member of the new PAC advisory board, said she has supported Chichester for a long time but acknowledged that Viguerie "is good at what he does."

Asked about the new PAC, Scott said, "Richard is the person to do it if it can be done."

If Viguerie reaches his goal of raising $400,000, his PAC would be the largest of its kind in Virginia legislative races, surpassing the spending of PACs that were active in the 1983 races. Those PACs were created by Republican Sens. John W. Warner and Paul S. Trible and Rep. Stan Parris of Fairfax.

Viguerie said the goal of the PAC is to elect 17 new Republican members to the 100-member General Assembly House in 1985. That would give Republicans, who now hold 34 seats, a majority of the House and power to control committee assignments and other key decisions. There are no elections in 1985 for the 40-member Senate, which also is controlled by the Democrats, 32 to 8.

State Del. Steve Gordy (R-Fairfax) said he believed a more realistic goal would be a net gain of six to eight House seats. The Republicans failed to make any gains in the last House races in 1983.