Democrats in Northeastern Fairfax County would like to make support of the Equal Rights Amendment the issue in next week's election for the area's three seats in the Virginia House of Delegates.

Republicans, after a bitter September primary that saw the ouster of one of their most controversial legislators, are running a campaign that stresses the seniority of the race's acknowledged frontrunner, Del. Vincent F. Callahan Jr., and downplays their candidates' division over the amendment.

Callahan, 49, a seven-term incumbent, and five political newcomers are competing in the newly created 49th House District, a district that includes the McLean, Great Falls, and Baileys Crossroads areas of Fairfax and the city of Falls Church. Winners in the Nov. 3 contest will serve a one-year term in the legislature, a session in which they will have to redraw the boundaries for the House's 100 seats following court rejection of the plan under which they are running.

All of the candidates describe themselves as moderates, except Republican Gwendalyn F. Cody, 59, who is a self-described Ronald Reagan conservative and an official of the Fairfax County Taxpayers Alliance. Unlike the other candidates, she is opposed to ratification of the Equal Rights Amendment and extension of the Voting Rights Act, which is pending before congress.

"I'm for the E-R but I'm not for the A," said Cody, a party activist who ran unsuccessfully in 1979 for the Fairfax Board of Supervisors. "The ERA is only an issue at these candidates meetings," said Cody, whose position on the amendment has made her a favorite target of the race's three Democrats.

"We all think she is the weakest link," said Elaine Lailas, 42, a former teacher at Northern Virginia Community College who placed first in the district's September Democratic primary. Her running mates are Conrad J. Marshall, 43, a McLean lawyer, and Flora M. Crater, 67, founder of the Virginia Women's Political Caucus, who ran a surprisingly strong race for lieutenant governor as an independent in 1973.

Both the GOP's Callahan and Robert T. Andrews, 61, a retired Defense Department lawyer, support passage of the ERA, which has never reached the floor of the Virginia House. It must be ratified by three more states by next June if it is to be added to the Constitution. The amendment would prohibit discrimination on the basis of sex.

The ERA has long been a more important issue in the Washington suburbs than in downstate areas. "ERA is an issue that can help a candidate win more than it can help a candidate lose," said Callahan.

With unanimity among candidates in the 49th District on most other issues, the ERA and the candidates' personalities have taken on greater importance, party workers say. "Basically it's going to come down to personality and image rather than the issues," said Nora Squyres, a Democrat who lost in the September primary. "There's not that much difference among candidates in the district."

Neither party questions that Callahan, the region's senior GOP delegate, is likely to return to Richmond. He received nearly twice as many votes in the GOP primary as Lailas did in her primary and is running so confidently he now trumpets the candidacies of his fellow Republicans as much as his own.

Callahan stresses his experience in the assembly, saying he wants the state to come up with increased funding for Northern Virginia's congested roads. The district's only other incumbent, Del. Martin H. Perper, a maverick Republican, was defeated in the primary.

Lailas, who taught secretarial skills at the college level, is making her first bid at elected office and has mounted one of the most aggressive Democratic campaigns in the district. Members of her campaign organization grumble that the Fairfax Democratic Party has not been supportive. They say that each Republican running in the district received a $1,000 contribution from the state Republican party, while Democrats have not been given a comparable party contribution.

Andrews, a retired government lawyer, is backing completion of the 101 mile-Metrorail system and capital punishment.

Democrat Marshall says he plans to seek revisions in several criminal statutes, including a change that would require a seven-year prison sentence for anyone convicted of using a firearm in a criminal act and making the penalties for daytime burglaries as severe as those for nighttime offenses.

Cody, who says she has never been discriminated against, says her major focus will be placing limits on taxing and spending and improving transportation in Northern Virginia, including construction of the Dulles Toll Road.

Crater concedes she is viewed as a one-issue candidate by voters because of her strong support for ERA. But she says that as a member of the State Democratic Central Committee she has drafted positions on a wide range of other issues, including support for the repeal of the state tax on food and the creation of a new department of transportation.