Call her the watchdog who came in from the cold. Sue V. Mills, the perennial Democratic outsider and self-proclaimed conscience of the Prince George's County Council, has decided she would like to be its chairman.

"I'm interested," said Mills, who has spent the last several days drumming up support from newly nominated Democratic council candidates. "I'm not going to shed any tears or blood over it," she said in a telephone interview yesterday, "but I'm interested . . . I didn't even ask the other members for a commitment. I just said I'm interested."

Mills said she had talked informally with several Democratic victors in last Tuesday's primary election, in which Mills was the only incumbent council member to win renomination by more than 50 percent. Seven of the 11 members of the present council were either defeated or ran for other offices, shattering the consensus that had dominated the council -- and excluded Mills -- for the last four years.

"Obviously the thought of taking charge crosses a person's mind once every four years," said Mills, who came to political prominence as an antibusing activist and school board member, "but with that group I knew I never had a chance."

In 1978, Mills, whose blond beehive hairdo and rousing rhetoric have become her trademark, was the only council member elected without the support of the county's powerful Democratic organization. Although she was the second highest vote-getter for an at-large seat, she never achieved a position of leadership.

Last year, when councilmanic district lines were drawn for the first time, she was placed in a predominantly black district, cut off from her conservative, majority white Oxon Hill base by a line drawn a few blocks from her house. Critics quickly predicted the end of her colorful career. But she simply moved into an apartment within the Oxon Hill district, told supporters she would build a house, and handily beat fellow incumbent David Hartlove.

In the past, Mills criticized the behind-the-scenes dealing that solidified support for the chairmanship years in advance, but she said yesterday that she is not averse to putting together a similar arrangement. "I don't see anything criminal about it," she said.

Her new stance has drawn mixed reactions from fellow nominees. One new member said, "She used to be one of the main critics and now she seems to be doing the same thing . . . But I'll listen to what she has to say."

Several other council incumbents have their own ideas about who should lead the council and will not let Mills take the lead without a fight.

"I've heard that Sue is crawling around trying to get some votes together," said Floyd Wilson, the council's most senior black member. "Maybe she is trying to put something together, but she hasn't come to me, and you know I don't love her. And I'll tell you what -- It's time for black leadership on that council. I've been jilted out of that before and as one of the senior members I feel it's time."

"I've been approached by some of the new members," said two-term incumbent Frank Casula, who declined to name them. "They feel I should possibly be the chairman of the new council." Casula said Mills "talked to me about it, yes, and I told her where I was coming from. I feel some of this is premature, the election isn't over yet. She just wanted the chair for this year and all I did was, I told her a couple of people have approached me."

In Mills' version, Casula had said, " 'No deals, I don't work any deals.' Then he leaned forward and said, 'Would you take the second year?' I just laughed. I said, 'I'd like the first year, Frank.' "

Mills noted that she had been chairman of the school board and says she was highly praised for her stewardship of that group. She wants to head the council "because it's a different experience," and, she says, because it's her turn.

"One of my dad's favorite expressions was, 'The devil will get its due,' " she said, "and sometimes I would say to him, 'Sometimes it takes a mighty long time.'"