Speculation about the intentions of Maryland Republican Sen. Charles McC. Mathias Jr. (R-Md.) has widened as a result of Nevada Republican Sen. Paul Laxalt's announcement that he will relinquish his seat next year and as GOP leaders search for ways to hold on to their six-seat Senate majority.

Mathias has not said whether he plans to run for a fourth term in 1986, and Laxalt's decision not to seek reelection has been interpreted by Republican strategists as a significant blow to GOP hopes for holding on to their 53-to-47 Senate margin next year.

While some Democrats said the departure of Laxalt, who is close to President Reagan, might actually lessen pressure on the politically moderate Mathias to continue in office, the chairman of the Maryland state Republican committee said he is "confident" Mathias would run.

But several of Mathias' aides and supporters said yesterday that he is unlikely to bow to any increased pressure brought about by Laxalt's resignation.

"Certainly party leaders in Maryland have been urging the senator to run for election," Mathias spokesman Randy Dove said. "But Sen. Laxalt's decision not to run has no bearing on what Sen. Mathias' decision would be. He has always made an independent decision."

Mathias was out of his office yesterday and could not be reached for comment. The Common Cause organization reported at the end of June that there was no money in the Maryland senator's campaign fund.

Republican National Committee spokesman Terry Wade said yesterday that no major overtures have been made to Mathias about running again.

"I presume there are [such discussions going on], but I have no knowledge of it," he said. "I really don't believe the Laxalt situation changes the equation for Mathias at all."

But Democratic National Committee spokesman Terry Michael maintains that "the scale has tipped in our favor for retaking the Senate" as a result of Laxalt's decison.

"Every single seat is going to count in 1986 toward our goal . . . . " he added. "Maryland is certainly on anyone's list of possibilities."

The Reagan administration has viewed Mathias, who has a moderate voting record -- his rating from the liberal Americans for Democratic Action in 1984 was 65 on a scale of 100 -- as a maverick in the Senate.

Former U.N. Ambassador Jeane Kirkpatrick and Donald Devine, who headed the federal Office of Personnel Management, have both been mentioned by Republican leaders as possible successors or challengers to Mathias.

Maryland state Republican party chairman Allan Levey said, however, that he is "confident" that Mathias will choose to run and will make that decision independent of Laxalt's action.

"It is not unusual for Sen. Mathias to wait for the fall of the year before the election to make a final decision," Levey said.

Jim Abbott, an aide to likely Mathias challenger Rep. Barbara Mikulski (D-Md.), said that the fallout from Laxalt's decision may actually lessen any pressure on Mathias.

"If the president's closest friend in the Senate can retire when he sees fit to, why can't Sen. Mathias do so also?" he said.

Abbott's sentiments were echoed by Baltimore businessman William Boucher III, who has raised money for Mathias as well as for Gov. Harry Hughes' gubernatorial campaigns. Hughes is one of several Democrats said to be considering a run for Mathias' seat.

"I'm waiting for both of them to make up their minds," Boucher said of Hughes and Mathias. "I have been a very strong admirer of Sen. Mathias and Gov. Hughes. I find them to be similar people with similar visions.