Audrey Scott showed off "Dear Marylander" letters signed by President Reagan -- or at least his signature machine -- and hinted at a visit by the vice president. Steny Hoyer rented a mansion and a tent for a 1,200-person fund-raiser that featured House Speaker Thomas P. (Tip) O'Neill, former vice president Walter Mondale and a dozen or so other well-known Democrats.

Nothing attracts attention as quickly as big names, and the two candidates for Congress in Maryland's 5th District took advantage of that fact this week to lift their campaigns out of the post-primary doldrums and gather some momentum for an election only three weeks away.

"Bluntly speaking, the national names give you media coverage and in a special election [such as that being held in the 5th District] you have to have it [coverage]," said Ann Lewis political director of the Democratic National Committee. "Your worst nightmare is that people will forget that there is an election on."

So, for the last week, the two campaigns have been working hard to win endorsements and set up events with their party heavyweights in order to assure voters in the district, which includes northern Prince George's County and Takoma Park, that each is the candidate of choice to replace Gladys Spellman, the former congresswoman who was incapacitated by heart arrest last October.

Scott got off to the quickest start in the famous name gambit with the distribution this week of the Reagan letter urging undecided voters to "cast [their] vote for Audrey Scott." But Hoyer scored the week's biggest coup in the effort to pull in well-known personalities with his fund-raiser Thursday evening at the Newton White Mansion in Mitchellville.

There, Mondale told a $100-a-person cocktail crowd, "the significance of this election nationally is as profound as it could possibly be." And House Speaker O'Neill said Hoyer's election would "send a message" that reductions in government are necessary "but there's got to be concern." In case the cameras or reporters missed the any of the endorsement speeches, all were repeated moments latter at a $10-a-person "bull roast."

After hearing of the Hoyer fund-raiser's success -- it will have raised some $60,000 when all the checks are in -- Scott campaign spokesman Jim McAvoy promised similar doings in his camp next week, with potential visits by Vice President George Bush and his wife Barbara among others.

But while both campaigns have been offering up national names this week in order to attract attention they have pursued other strategies as well. These include:

Appearing at candidates nights. These forums have elicited substantial agreement between Hoyer and Scott on many national issues, including the need for reductions in government spending. Scott has used the debates to publicize her support of the Reagan budget and desire to provide constituent services. Hoyer has touted the alternative Democratic budget and emphasized his experience during 12 years in the state Senate and as Senate president.

The debates have also been attended by Christos C. Poppos, a write-in candidate, and Tom Mathers, a libertarian candidate who may appear on the May 19 ballot if he wins a May 6 court battle with the state over election procedures.

Sending out press releases that attack their opponent. While the charges and countercharges are frequently over minor issues, they have nonetheless created a somewhat testy campaign atmosphere in the last week.

Scott, in particular, has employed this method, accusing Hoyer of not writing enough issue papers and being untrustworthy because he did not resign from a politically sensitive redistricting commission immediately after the April 7 primary. Hoyer, who has since resigned from the commission, responded by accusing Scott of breaking a promise of her own to not run for office while serving as the nonpartisan mayor of Bowie. His campaign manager also charged that Scott, the underdog, has run a negative campaign based on "falsehoods, innuendo and flashy media paid for by outsiders."

Returning to the telephone banks and direct mailings that helped both candidates through their crowded primaries. Both candidates are making calls to likely voters -- Scott with a paid staff, Hoyer with volunteers -- and have begun distributing leaflets and mailing brochures to make sure their names are known on May 19.