Maryland's Democrats, who with two weeks remaining before the election appear to have commanding leads, brought their version of overkill into the state yesterday: former vice president Walter F. Mondale.

Mondale, who has been campaigning nationwide this year as a hopeful 1984 Democratic presidential nominee, was at ease campaigning with Democratic incumbents in one of only six states that he and former president Jimmy Carter carried in 1980.

"I don't have to tell you Marylanders about Reaganomics," Mondale said at one point yesterday. "You already knew it was a bunch of junk two years ago."

Mondale made speeches yesterday afternoon in Silver Spring and Bowie. The speeches differed vastly in style and tone, but both carried the same message: "This is as important an election as we've had in this country in at least 20 years. The issues are as great, the differences as deep, as any I've seen in all my years in public life . . . . The president's economic policies are not moderate or conservative; they are radical. So let's send a message to Washington on election day."

That was the basic theme on a cool, gorgeous autumn day as Gov. Harry Hughes, U.S. Sen. Paul S. Sarbanes, U.S. Reps. Steny H. Hoyer and Michael Barnes, state Attorney General Stephen H. Sachs and Comptroller Louis L. Goldstein took turns using the Republican administration as a punching bag.

After speaking in Silver Spring and Bowie, Mondale spoke twice more in Baltimore last night, as part of what had been designated National Labor Solidarity Day. He arrived at the first of his four scheduled stops looking so tan that the chronically tan Hughes commented: "He's been campaigning in Florida. No fair."

After delivering his golden words for Hughes, Mondale turned and looked at the tall, wavy-haired governor and said, "You know, if I looked like him I might have made something of myself."

This was the tone all day, with the confident Democrats clearly having a good time. Goldstein warmed up the crowd with the folksy routine he has been employing since first he was elected comptroller in 1958. Sachs followed and complained about having to follow Goldstein. He also began the serious speeches: Sarbanes must be reelected because he is a good senator and to "send a message a popular phrase on these trips to NCPAC" (the National Conservative Political Action Committee), which has spent more than $600,000 in a media drive to try to defeat Sarbanes.

Sachs was followed by Barnes and Hoyer at the first rally, held in Jessup Blair Park in Silver Spring. Barnes told the gathering of about 150 union leaders and members that "for a working man or woman in this country to vote Republican in 1982 would be a like a chicken voting for Colonel Sanders."

The only reference to the Democrats' Republican rivals in Maryland during the first two stops was brief, with Hughes observing, "If you compare this ticket to the Republican ticket -- that is if you know anyone on the Republican ticket -- you'll realize there's no comparison."

But the best came last.

"I'm speaking last?" Mondale said when informed of the speaking order. "That's okay, I'm used to being on the bottom."

Mondale started by noting that Hoyer "must be a very popular politician. I appeared in public with him last year and he still got elected."

Mondale then turned serious, saying of NCPAC: "These people are vicious, pernicious, cowardly and irresponsible. They won't even stand up and attack a man's personality and stand behind it. They do it anonymously. That's why we have a special job in Maryland this year, to tell these people they have no place in our state and no place in our political process."

At a Bowie library an hour later, a low-key, almost conversational Mondale told members of the National Association of Retired Federal Employees: "I'll always be on your side. After all, I'm a retired federal worker, too."

The rest of his speech was an attack on Reagan's Social Security cuts and his dealings with the elderly and with retired federal workers. In both speeches, Mondale said, "I've traveled this entire country, and Harry Hughes is the best governor there is in any state."

Afterward, Mondale was asked if he had used that rhetoric on other governors elsewhere.

"Well, uh, he is a superb governor," Mondale said. Then he added: "I won't back away at all from what I said. I stand by it."

But when a television reporter asked if he might consider Hughes as a 1984 running mate, he quipped, "This state is full of vice presidential possibilities. You look like one."