When Fred Wineland resigned as Maryland's secretary of state last summer, State Sen. Thomas V. Mike Miller, the head of the Prince George's County Senate delegation, secured a commitment from Gov. Harry Hughes that the successor to Wineland--a Prince Georgian--would also be from the county.

Miller thought that promise solved a problem, but instead he had opened a political Pandora's Box.

"If there's one person in this county who wants the job, there's 100 of them," Miller said this week. "Right now, I'm not even in a position to recommend anyone to the governor. Any position I take could cause me a problem."

Among those who want the job is former county executive Winfield M. Kelly Jr. After a four-year exile from politics, Kelly is "dying" to get back in, according to friends. Kelly, who spoke with Hughes about the job in Ocean City last summer, said today that he was interested and might ask for a meeting with the governor.

The once largely ceremonial job has taken on new responsibilities in recent years, and beginning in 1983, at Hughes' recommendation, the salary will be $45,000 a year, up from $36,000. Despite the new duties, the secretary's main claim to fame here is as keeper of the state seal.

But the salary and prestige have produced a list of applicants, including State Sen. Mary Conroy, wife of the late senator Edward T. Conroy; Sen. B. W. Mike Donovan; former senator Meyer Emanuel; Del. Pauline H. Menes; Del. Kay G. Bienen; Register of Wills Callie Mae Heffron; Bob Banning, businessman and longtime party fund-raiser; former county council member Sarah Ada Koonce and the incumbent acting secretary, Pat Holtz.

Miller had hoped that Hughes would come to him this week with two or three names, but that now seems unlikely. "He's not even focusing on that one yet," said a Hughes staffer. "It will be at least another week, maybe two, before he makes a decision."

Although Kelly, 46, is no longer close with longtime county political powers Peter F. O'Malley and Rep. Steny H. Hoyer (D-Md.), his appointment would, in the eyes of the Hughes people, solidify their relationship with that wing of the party. "I indicated to the governor this summer that I had an interest in the job and I still have that interest," Kelly said today. "I haven't made contact with him about it lately, but I wouldn't hesitate to. I didn't realize a decision was right on the horizon."

When Kelly was beaten four years ago in his bid for reelection by Republican Lawrence J. Hogan, he said he was getting out of politics to concentrate on business.

Since then he has become heavily involved in cable television as owner of Storer Communications.

He said today he would like the secretary of state's job because it is "a statesmanlike position." And he did not rule out the possibility that an appointment could be a first step toward seeking elective office again.

"I would say that I'm pretty flexible," Kelly said.