With less than a week to go before what is billed as the make-or-break Senate hearing, the White House is under heavy political pressure to rescue the embattled renomination of Office of Personnel Management director Donald J. Devine.

Conservative groups are warning that if Devine's nomination is shot down, it will signal congressional Democrats that they can blitz the media again to block future Reagan nominations.

Although Republicans hold a 7-to-6 edge over Democrats on the Senate Governmental Affairs Committee, the White House has been warned repeatedly that Devine doesn't have the votes to win another four-year term.

The Washington Post reported yesterday that only three senators on the committee now plan to vote for Devine. The former University of Maryland professor's first term expired in March. Devine resigned several weeks ago from a temporary job as an assistant to acting director Loretta Cornelius.

Committee Democrats say Devine politicized the top merit system job by campaigning last year for Republican congressional candidates. They also contend that he may have violated federal rules by delegating authority to himself to run some OPM operations while serving as deputy to Cornelius.

Since he left the OPM, Devine has been working for the Heritage Foundation, a conservative think tank.

On May 10 a dozen GOP senators, including Reagan intimate Paul Laxalt (R-Nev.), wrote the president urging him to "pay urgent and careful attention" to Devine's renomination.

That letter, a copy of which was obtained by The Washington Post, said that there are "many compelling reasons for your continued support of Don, and significant negative consequences should you not strongly support" him.

The letter was signed by Laxalt and Sens. Strom Thurmond (R-S.C.), Paula Hawkins (R-Fla.), Jesse Helms (R-N.C.), Jeremiah Denton (R-Ala.), Orrin Hatch (R-Utah), Chic Hecht (R-Nev.), James A. McClure (R-Idaho), Malcolm Wallop (R-Wyo.), Steve Symms (R-Idaho), James Abnor (R-S.D.) and Phil Gramm (R-Tex.).

It cited Devine's record at OPM and his strong support of Reagan programs to trim the bureaucracy.

"More important," it said, "Don's nomination has become a signal vote . . .a test of Democrats' ability to use publicity to bury Reagan nominations. We believe that if White House strength is not visible and if the nomination is not passed, it will be increasingly difficult to confirm those nominees who are most likely to carry out your aims."

The letter said that Devine has been through "grueling" congressional hearings and was the target of "critical press report after critical press report."

Not all the press on Devine has been critical, however.

In an editorial Tuesday, The Wall Street Journal strongly endorsed Devine's renomination and warned: "If the president can't save one of his brightest stars the wolves will become bolder."

In its May 20 edition, The Detroit News editorialized that Devine is the victim of an "ugly little game of inside-Beltway baseball." It said Devine's proposals to cut the federal retirement program have mobilized the bureaucracy and unions against him.

"Congress won't change the truth by killing the man who delivers that important message. So it should permit Mr. Devine to continue his work," the newspaper said. Senior Executive Association

The organization representing many of the government's top career managers will celebrate its fifth birthday Friday evening at the Shoreham. SEA has increased the clout of careerists with Congress and the White House, and won executives a big back pay settlement.