ythe Reagan administration came to this old port town for a double-decker bus tour of reviving inner city neighborhoods and the flourishing harbor, an event that marked a coup of sorts for two Maryland politicians on opposite sides of the political fence.

Democratic Mayor William Donald Schaefer, whose city voted overwhelmingly Democratic last November, finally was able to show off the city's federal aid-induced rejuvenation in an effort to improve Baltimore's standing with the White House.

Republican Rep. Marjorie Holt, who brought HUD Secretary Samuel Pierce, Rep. Jack Kemp (R-N.Y.) and others on the tour, had her first chance to show the vote-rich city that she has clout with the White House and is working to help the city despite its Democratic traditions -- important factors as she prepares to run for U.S. Senate against Democratic incumbent Paul Sarbanes.

So it was not surprising today that the two politicians spent much of the bus tour avoiding all partisan political talk and simply agreeing again and again how wonderful Baltimore is.

"I don't look on this as Republican-Democrat," said Schaefer, the city's leading booster. "I look on this as the Reagan administration trying to help people. This is a very friendly visit today."

Said Holt, "This is an opportunity for [the Republicans] to visit the City of Baltimore, which is the heart of Maryland, and see the great things that Mayor Schaefer has done here."

Although politics was hardly mentioned, it was very much a part of the two-hour trip on a charter bus accompanied by a police escort, that took the officials and a phalanx of Schaefer's public relations aides from homesteading sites to rejuvenated inner city neighborhoods and Harborplace.

Since the presidential elections in November, Schaefer, whose close relationship with the Carter administration ensured that the city was a showcase for federal aide programs, has been faced with the loss of hundreds of millions of federal dollars.

The mayor has spent weeks at a time on Capitol Hill in an effort to persuade Congress to reverse many of the Reagan budget cuts and has attempted to convince the White House to target Baltimore for their federal aide experiments.

While Schaefer and members of the Baltimore business community have met with some White House advisors, until today no one in the Reagan administration and none of the influential Republicans had shown any interest in seeing Baltimore first-hand.

So it was that Holt, who arranged the tour after breakfasting recently with Schaefer, was able to take credit today for acting as the state's most effective liaison to the administration.

Holt, like many Republicans running in primarily Democratic areas, hopes that will convince some voters in this decidely democratic city that it is in their best interest to vote Republican.