Marvin Mandel has asked President Reagan to order his early release from prison and has enlisted a pair of unlikely allies -- Sen. Paul Laxalt (R-Nev.) and Rep. Jack Kemp (R-N.Y.) -- to support his request.

The involvement of two of Reagan's closest political friends is considered a crucial element in a last-ditch effort by the former Maryland governor to win early release from the federal prison camp in Florida where he is serving a three-year term for political corruption.

Laxalt, who, according to an aide, "sees no useful purpose in Mandel serving out his entire term," has agreed to personally deliver to Reagan a petition supporting the president's use of executive clemency to shorten Mandel's sentence. Kemp already has spoken to presidential counselor Edwin Meese III and White House Counsel Fred Fielding about Mandel's clemency request, sources said.

The petition supporting the clemency request was signed by most members of the Maryland congressional delegation and a wide variety of influential local Republicans when it was circulated during the last two weeks.

Mandel, who has served 17 months at the Eglin Air Force Base prison camp for his political corruption conviction, has exhausted all other means for early release, having appealed for an earlier parole date all the way up to the U.S. Parole Commission. The commission last year ordered him to remain in prison until next May -- in essence, serving almost his entire term, despite recommendations by federal prosecutors that he not be forced to remain imprisoned for the full period.

This week, one of Mandel's attorneys filed a petition in federal court in Florida asserting that the parole commission used inappropriate guidelines in Mandel's case and seeking his immediate release. A similar appeal was successful for one of Mandel's codefendants, but the case took months to resolve, and with Mandel scheduled for release in seven months, a decision in the case could be moot.

Mandel supporters have made individual attempts, through letters to the parole commission and the White House, to secure his early release, but the formal clemency request and petition drive have been the most elaborate and well-orchestrated efforts undertaken in the former governor's behalf.

"Enough is enough has been the whole theme of this effort," said Bruce Bereano, the Annapolis attorney hired by Mandel last year to work for his release. "We're looking toward presidential relief if the president considers it appropriate. It is our greatest hope."

Bereano and Arnold Weiner, Mandel's attorney throughout his trials and appeals, recently met with Fielding, the White House counsel, after filing the formal request for clemency. The request went through Fielding's office and is now being reviewed by the Department of Justice. The department must make a recommendation to Reagan, but because the granting of clemency is one of the most unrestricted presidential powers, Reagan could shortcut this process at any time, according to legal sources.

Bereano will say little about the highly sensitive campaign to win executive clemency for his client. But other sources said Mandel supporters "were running into difficulty getting through the many layers of people to the top at the White House." That, according to these sources, was where Kemp and Laxalt came into the picture, and the connection to Kemp, at least, was roundabout.

Bereano spoke to a friend, who is the brother of Kemp's administrative assistant, David Smick. Then he spoke with Smick, and soon was able to meet with Kemp.

Sources said Bereano came for advice, and the basic advice he got was, "Get to Meese." Kemp spoke personally with Meese about the case, and an aide in his office spoke to other key White House advisers.

Kemp, said one source, "is obviously not an expert on the parole process, but his leaning is that the man Mandel should be given consideration for some type of early release. He wanted to make sure the Mandel situation did not fall through the cracks at the White House."

The approach to Laxalt, who briefly met Mandel at a governors conference when Laxalt was governor of Nevada in the late 1960s, was more direct. Bereano called his office for an appointment and went to see him with Abe Pollin, the owner of the Washington Bullets who has been quietly working for months on Mandel's behalf.

The idea for a letter to the White House signed by influential Marylanders was born shortly after that meeting, and Laxalt, according to aide Ed Allison, was "supportive" when told about it. The letter, turned over to Laxalt late Tuesday and written on Pollin's Capitol Centre stationery, has 27 signers, including all but two of Maryland's eight congressmen and such influential Republicans as Prince George's County Executive Larry Hogan and state GOP chief Allan Levey.

The letter also was signed by Rep. Kent Hance, the Texas Democrat who cosponsored Reagan's tax bill. Hance offered his signature, he said, because "Mandel is not getting the same fair shake as any ordinary citizen. I'm from West Texas and nobody out there ever heard of Marvin Mandel, but I think the guy should be released."