Maryland Sen. Paul S. Sarbanes (D) took the first real offensive in the U.S. Senate campaign in Maryland last night, charging that GOP challenger Lawrence J. Hogan had failed to prevent an "extremist group" from manipulating the political process in the campaign.

In an angry exchange, Sarbanes said the National Conservative Political Action Committee (NCPAC), an independent group that has spent $625,000 on a 15-month media campaign against him, would have left Maryland if Hogan had pressured it to do so. "You ought to get them out of the campaign," he declared.

Hogan returned the fire, saying that Sarbanes was using NCPAC "as a smokescreen" to distract voters from his voting record. "NCPAC is not on the ballot," Hogan said to Sarbanes. "Let's debate the real issues." He said he has "repudiated NCPAC at every turn."

The exchange came during a testy 60 minutes aired on WMAL radio during which the candidates swapped charges and countercharges on NCPAC and Reaganomics.

Sarbanes stuck with the NCPAC issue, repeating several times that Hogan had the power to get the group out of the state if he had wanted to. He said Hogan could have been more vocal in opposing NCPAC and could also have contacted the group and broken their independence as a political entity.

According to Sarbanes, Hogan would need only provide the group with some information about the Hogan campaign to involve it in his camp and prevent it from spending unlimited amounts of money in the state. Under present law, NCPAC, as a group independent of all candidates, can spend well beyond the $5,000 in contributions that limits most political action committees that make direct contributions to electoral campaigns.

Hogan said his lawyers have told him it would be against the law for him to contact the group.

"You're trying to wrap NCPAC around my neck," Hogan said.

NCPAC began its advertising campaign against Sarbanes last year, drawing attention and money to what some Republicans had hoped would be a campaign by a vulnerable Democrat. In August, NCPAC resumed its advertisements, which appeared on alternate weeks from advertisements televised by the Hogan campaign. At that time, Hogan said he didn't mind any group that "was saying nice things" about him.

Although NCPAC engendered the angriest exchanges between the two, Sarbanes and Hogan spent equal time debating the merits and demerits of Reaganomics.

Sarbanes said the Reagan administration's policies had precipitated "a major economic crisis" that was reflected in an unemployment rate that now stands close to 10 percent.

Hogan, echoing President Reagan, said today's economic woes could be blamed on 20 years of Democratic rule in Congress. He accused Sarbanes of supporting economic policies that had contributed to the enormous national deficit and to the current high interest rates.