At the State Department, they gave him high marks as a good listener. At the mock television studio on 14th Street, they found he was a "natural in front of the camera." and back at campaign headquarters they call him a "fast read." In fact, they wish he wouldn't read so much.

That's the assessment so far in the schooling of Edward T. Conroy -- the hurried and harrowing process of fashioning a U.S. Senate candidate out of a Maryland legislator whose biggest crusade this term was stopping a statewide increase in truck weights.

Yesterday, the results of media consultations, a State Department briefing went on display for the first time, as Conroy officially opened his campaign against the poppular Republican incumbent, Sen. Charles McC. Mathias Jr. a

At a press conference in the Elks Hall that is Conroy's Silver Spring headquarters, the Democratic candidate attacked the incumbent on everything from Mathias support last year for an amedment to cut defense spending to his vote against an amendment to balance the federal budget.

"Charles Mathias is out of step with the people," Conroy told his audience. "he and the policies he repesents will b e ejected in November."

Mathias' aides seemed unimpressed by the attack. "The surprising thing to us," said press aide Jack Eddinger, "is it's virtually a carbon copy of some candidates' attacks in the primary. You would think having seen it go down to defeat then, the candidate of the majority party wouldn't use it again."

But Conroy, unlike some of Mathias' previous Demoncratic challengers, is trying to follow a conservative path that will leave him well to the right of the low-key liberal incumbent; particularly in the area of defence. And at least some of his political schoolingin the past months reflects just that intent.

On a quiet, Saturday morning during the primary Conroy and an aide met with retired Army Lt. Gen. Daniel Graham, who once was the Pentagon's chief intelligence officer, for a briefing on defense.

Graham has occasionally served as a spokesman for the American Securitiy Council a conservative group that favors a tough defense stance and a hawkisk policy toward the Soviet Union.

In their meeting Graham and Conroy talked about national security issues and defense in a session that lasted five hours and in which the two former Army men "hit it off really well," according to campaign chairman Dennis Devaney.

But that was just the beginning of the veteran state senator's course in national afairs and statewide candidacy.

Since then there has been a three-hour briefing at the State Department provided by Stephen Ledogar, director of the office of NATO affairs, whose job often entails schooling congressmen and federal candidates in the intricacies of foreign policy.

Then there was the visit to the mock television studio of public relations consultant Bill Rhatican, conservative Republican whose admirers tout him as "supersalesman for the New Right."

There, under the hot, white lights and in front of a television camera, Rhatican shot questions at Conroy, "trying to nail him to the wall and see how he reacted," Rhatican recalled.

And how did Conroy do? "I loved him, oh absolutely loved him," said Rhatican. "He's one of the few politicians i've met who's natural on TV.

And what did the freshly minted U.S. Senate candidate learn from the $250-an-hour sessions?

"That on TV, you shouldn't wear jewelry," said Conroy, showing how his tie clasp could glare under the lights. "And that men have ugly calves," he noted, as he showed off the new longer socks he's wearing so he won't have that problem on television.

Conroy's aides and two college students have been researching Mathias' 12-year record in the Senate and Conroy has been reading their findings voraciously as he sits in his big, black Lincoln on the way to campaign functions and meetings.

"I don't like to be unprepard when i talk about issues," said the 51-year-old senator, who in the days following the May 13 primary adamantly refused to discuss them until his research was done.

"He's done his homework," Conroy consultant Jack Mongovern beamed yesterday after the senator's press conference.

"People underestimate Ed." said longtime friend Devaney. "But he's a fast read. If you give him the information, he's good."