ANNAPOLIS, JUNE 12 -- Sure it was an old endorsement, but it was still in good shape. Only used in one election.

That didn't stop fellow Republicans from crying foul this week after Wayne T. Gilchrest, a candidate for Congress from Maryland's 1st District, ran a radio ad that included an endorsement from Ronald Reagan.

Gilchrest neglected to note in the radio spot that Reagan's endorsement was for the 1988 general election, when he surprised almost everyone by nearly unseating Rep. Roy P. Dyson (D).

"We didn't intend to mislead the public," Gilchrest, a Kent County educator, said in an interview today. "Maybe we should have" said it was an old endorsement not intended for use against fellow Republicans.

Gilchrest said he called Reagan's staff on Monday and was told to stop using the tape. "I'm going to take their advice," he added.

The 45-second radio spot included "man-on-the-street" interviews in which the speakers invariably said they were going to vote for Gilchrest in the September primary. At the end, Reagan's voice added, "I'm not the kind of fellow who tells other people how to vote . . . . Well, I like Wayne Gilchrest."

Gilchrest said he had not considered the propriety of reusing the endorsement until one of his opponents in the Sept. 11 primary, Luis Luna, telephoned to complain. Some of the other six Republicans in the race sent word that they did not appreciate the tactic, Gilchrest conceded.

"It's sad that it's come to this," said Luna. He said he took his complaint to Reagan's staff and to the National Republican Congressional Committee.

What particularly upset some of Gilchrest's opponents was the timing of the radio commercial, which was broadcast Friday and Monday on stations in Easton, Salisbury and Baltimore. During that period, the NRCC was polling the district, which covers Southern Maryland and the Eastern Shore. Republicans expect the survey results to help persuade some of the lesser-known GOP candidates to bow out.

"This was an attempt to bump the numbers," Luna said of Gilchrest's ad.

The closeness of the 1988 race has brought a flood of Republicans out seeking a chance to challenge Dyson, who will face Del. Barbara O. Kreamer of Harford County and Harford County lawyer Michael Hickey in the Democratic primary.

Besides Gilchrest and Luna, the current Republican field consists of Perry Weed, a lawyer from Talbot County; Raymond J. Briscuso, a lawyer who helped lead President Bush's campaign in Maryland; state Del. Richard Colburn of Dorchester County; Calvert County Commissioner Mark Frazer; Barry Sullivan, an engineer in Calvert County, and Charles Grace of Harford County.

"The best thing they could have done was to ignore the ad," Gilchrest said. "Now it's attracting a lot of attention."