Ronald Reagan may be long gone from Washington, but he still has a place in the office of Rep. Beverly B. Byron of Maryland. There, amid an avalanche of military paraphernalia -- including personalized coveralls and a citation for flying aboard a supersonic spy plane -- are four pictures of Byron and Reagan together.

Byron is a Democrat, Reagan a Republican. And the political link between the two -- bedrock conservatism -- has ignited the first sparks in her reelection campaign this year.

As Byron, 57, completes her sixth term representing Maryland's 6th Congressional District, she has come under attack for allegedly abandoning the Democratic Party in everything but name. Her opponent in the Sept. 11 primary, Potomac businessman Anthony P. Puca, cites studies that show her voting record is among the most conservative of all House Democrats. He likens her philosophy to that of GOP stalwarts such as Minority Whip Newt Gingrich (Ga.), saying, "We have a Republican congresswoman."

There are strong signs that many 6th District voters support Byron's conservative bent. The district includes the western part of Montgomery and Howard counties and some of the Baltimore suburbs, and sprawls west to the West Virginia line, encompassing small towns and rural counties that are markedly less liberal and less affluent than Maryland's urban areas.

Reagan won the 6th District 2 to 1 in 1984. Maryland's Democratic senators, Barbara A. Mikulski and Paul S. Sarbanes, narrowly carried the district in their last races, even though both won by large margins statewide. Byron lobbied for a federal prison under construction near Cumberland because it will bring the area 250 jobs. She has never had a close race in six previous elections.

But Puca's attacks are quietly echoed by some Democratic Party activists, who say she is well to the right of the party regulars likely to turn out for the primary. Two years ago, Puca ran a largely inactive campaign against Byron and got 19 percent of the vote. This year, his message and his more vigorous campaigning have attracted Byron's attention.

Three Republicans -- Christopher P. Fiotes Jr., of Gaithersburg; Frank K. Nethken, of Cumberland; and Kenneth Warren Halsey, of McHenry -- also are competing in a Sept. 11 primary, with the winner to take on the Democratic victor in November.

Byron, asked about her portraits of Reagan, replied, "I've got pictures of Jimmy Carter in the other room. I've got the recent pictures in here.

"There are those that get angry with me on a regular basis and wish I would change a vote or two," she said. "But I think the majority of {district residents} are comfortable with my voting record."

Puca disputes that. "This is a district made up of traditional Democrats, liberals and working people, but Beverly Byron votes against everything that would benefit the middle class," he said. "If I win, we put in a good, liberal Democratic vote and take away a very bad, conservative vote."

Byron's brand of politics is part of a long tradition that binds her family and her constituents. She is the fourth Byron to represent Western Maryland in the House, having inherited the seat when her first husband, Goodloe, died of a heart attack in 1978. Goodloe Byron's father, William, held the seat in the 1940s, and was succeeded upon his death by his wife, Katherine.

"Within 24 hours I was a widow, a single parent, unemployed and a candidate for Congress," Byron said recently. "There was no campaign. I made no appearances and no speeches. I didn't take any contributions. And a month later I was in Congress."

From the beginning, Byron's philosophy has mirrored that of her late husband, who once was called the House's most conservative Democrat outside the South. But she has put her own stamp on the job, making defense issues her priority, although the district has no major military bases.

Byron is chairman of a House Armed Services subcommittee that oversees pay and benefits for uniformed personnel. Like many Armed Services members, she has traveled extensively in the United States and abroad, logging 11 taxpayer-financed foreign trips in the last three years.

Committee colleagues describe her as a serious and hard-working member, although not a prominent voice in policy debates. Her subcommittee spends most of its time on matters such as health insurance and child care, issues that confront any large employer. She is preparing legislation that would grant severance benefits to military personnel expected to be laid off because of defense cuts.

In the past, Byron has supported more military spending than most Democrats, and shows no sign of change. "A lot of colleagues of mine talk about the 'peace dividend' and feel we can gut our defenses," she said. "There's no question in my mind we can draw down the total defense structure. But we're not going to do it overnight."

Puca, by contrast, believes sizable reductions in defense are in order. "All the money we spend on the military we no longer have to spend on other things," he said. "I would cut $30 billion or $40 billion from defense in the first year. We need more for child care, more for housing, more for a host of needs."

On a wide range of issues, Puca and Byron are opposites. Byron voted for a constitutional amendment banning flag-burning; Puca opposes it. Puca believes the Supreme Court decision that legalized abortion should not be altered; Byron favors a constitutional amendment that would mark the beginning of life at conception.

Byron supported President Bush's proposal last year to cut taxes on capital gains; Puca opposes it, and favors raising the income taxes of those who earn more than $100,000 a year.

Puca, 42, contends that Byron has held her seat so long because she has never faced a credible challenger.

But the political odds against Puca appear to be long. He has run unsuccessfully for several political offices since the early 1980s. He made a strong bid to unseat Montgomery County state Sen. Laurence Levitan (D) in 1982, in a campaign that drew widespread attention for its nasty tone. Puca put his name on the ballot against Byron in 1988 but said he did not "campaign a day or spend a penny" because his daughter became ill.

The 6th District race promises to offer a marked contrast to the big-dollar, high-technology campaigns that are increasingly common for House seats. Puca said he has raised about $9,000 and hopes to take in about $125,000. Byron's office, unlike that of many incumbents, generates a limited amount of computerized mail and her campaign has only about $100,000 on hand.

But Byron said that although the campaign may be low profile, it will not be low intensity.

"I've never had a close race," she said. "And I don't aim to have one."