MANCHESTER, N.H., SEPT. 25 -- Former U.N. ambassador Jeane J. Kirkpatrick tonight dampened the brush fire of speculation in this state that she might enter the Republican presidential race, but she declined to stamp out the embers.

"I have said no, I don't expect to be a candidate," she said at a news conference. But when asked whether there is no possibility that she would enter the race, she said, "I don't answer questions like that. . . . I can conceive of lots of things."

Later, one of the major promoters of a Kirkpatrick presidential bid, former New Hampshire governor Meldrim Thomson, said, "She is not a candidate, but she didn't say she wouldn't run if certain circumstances gelled. . . . She left the door open."

Thomson is one of a small group of New Hampshire Republicans who had been supporting former senator Paul Laxalt (R-Nev.) until Laxalt declared he would not enter the race. Tonight, Thomson said of Kirkpatrick, "I have the gut feeling she would make a great president," but added, "she's got to want to run" if she's going to get in the race this date.

Kirkpatrick refused to rate the six Republicans now in the race, contending that she is "a journalist" who should not get into the process of making judgments. She was, however, more than willing to make judgments in response to questions on policy issues, including asserting that the War Powers Resolution is "manifestly unconstitutional," that Supreme Court nominee Robert H. Bork is "a man of great integrity and real intellectual distinction" and that the Reagan administration's handling of the Persian Gulf crisis has been a "reasonable response."

To mark Kirkpatrick's visit to this state where the first presidential primary will be held Feb. 16, Nackey Loeb, publisher of the conservative Manchester Union Leader, wrote a front-page editorial declaring:

"We are honored by her presence, for here is a most able and unusual person. . . . When Jeane Kirkpatrick speaks, people listen. Jeane Kirkpatrick, we welcome you to New Hampshire and you can be sure that many of us will be listening to what you have to say."

Joseph W. McQuaid, vice president and editor-in-chief of the Union Leader, said, "I think she {Kirkpatrick} would beat. . . this group," referring to the six Republican candidates in the race.

Others, however, are less enthusiastic. Gerald Carmen, head of the organization sponsoring Kirkpatrick's visit, Citizens for America, cautiously noted, "I don't think it's too late for someone to get in the race. . . who has a reason to be in the race."

Carmen's son, David, who accompanied Kirkpatrick here, said, however: "I think it is late. It's possible, I suppose, but just. The groundwork is difficult. Even if you could win in New Hampshire, there is all the rest of the country."

In private, strategists for such candidates as Vice President Bush and Rep. Jack Kemp (R-N.Y.) argued that almost all the Republican leadership in New Hampshire is committed to other candidates and that, consequently, Kirkpatrick would find very little support.

"She would run into the same roadblock as Laxalt -- there's hardly anyone left for her to pick up," one said.

Kirkpatrick last Sunday received support for a presidential bid from the conservative San Diego Union where Ed Fike, chief of the editorial page, wrote that with the Kemp campaign "almost hopelessly trailing, the way is now wide open for conservatives to entertain alternatives. . . . {Kirkpatrick} would provide the 1988 race conservative horsepower, and she would inspire armies of zealous precinct workers." The commentary was repeated in part by the Union Leader.

Kirkpatrick's appearance at the Citizens for America fund-raiser as the keynote speaker for a "Salute to Jerry Carmen" drew sales of at least 500 tickets, at $50 and $200, depending on whether the purchaser wants to go to a cocktail party with the former U.N. ambassador. Carmen cut his political teeth in New Hampshire when he engineered the upset write-in victory of Henry Cabot Lodge in the 1964 primary.