Jeane J. Kirkpatrick, who for months has been discounting reports that she might enter the Republican presidential sweepstakes, yesterday switched gears to signal interest in getting into the race.

In what appeared to be a well-orchestrated sequence, former New Hampshire governor Meldrim Thomson held a news conference in Concord at which he described the former U.N. ambassador as "being within a hair of running."

Thomson said he met with Kirkpatrick this week and that she told him, "I'm going to do it; I'm going to do it."

Mark Salter, an aide to Kirkpatrick here, then issued a statement that "she is seriously considering the suggestion that she become a candidate for the nomination largely because she's not satisfied that the pressing issues that should be discussed in the campaign are being dealt with adequately." He declined to identify the issues.

Last month in Manchester, N.H., Kirkpatrick, a former Democrat, told a news conference, "I am not a candidate . . . I have said no, I don't expect to be a candidate."

If she gets in the race, many observers think that she will be most damaging to the faltering campaign of Rep. Jack Kemp (R-N.Y.), an assessment Kemp strategists appear to share.

Kemp spokesman John Buckley said her entry "would be by no means a fatal blow, but it would increase the chances that one of the two moderates, {Vice President} Bush and {Sen. Robert J.} Dole, would be the nominee. . . . Given the fact that neither of them has been specific on SDI {Strategic Defense Initiative}, that neither of them has proposed $310 million in new aid to the contras, any action by her that would increase their chances of getting the nomination would be counterproductive to those issues that she is interested in."

Kirkpatrick's consideration of the race reflects the disarray of the GOP's political right, which has been unable to settle on a presidential candidate. Kemp has picked up some support of the conservative wing of the Republican Party, but his drive has been damaged by the success in early caucuses and straw polls of former religious broadcaster Marion G. (Pat) Robertson.

A Bush strategist, who asked not to be identified, claimed to be pleased with the prospect of Kirkpatrick's entry. He said it would further divide the right, and it would almost guarantee that the Manchester Union Leader would endorse Kirkpatrick. New Hampshire has become a "must" state for Kemp.

Edward Rollins, Kemp campaign chairman, said Kirkpatrick's entry could hurt Kemp's chances in New Hampshire.

"Obviously, Jeane Kirkpatrick is not going to be a viable candidate beyond New Hampshire," he said, but in that state "she will pick up the support of conservatives who are still looking and the support of the paper {the Union Leader}, and that could hurt."

In addition, those considered likely to support a Kirkpatrick campaign include Nackey Loeb, publisher of conservative Union Leader; former representative John Le Boutillier (R-N.Y.); pollster Arthur Finkelstein; Lyn Meyerhoff, a fund-raiser from Baltimore, and Sofia Casey, widow of the late CIA director, William J. Casey, according to sources close to Kirkpatrick.

In a separate development, Sen. Warren B. Rudman (R-N.H.) is expected to announce his endorsement of Dole on Monday. Rudman will conduct a four-city tour through the state to promote his declaration.