White House political adviser Lyn Nofziger yesterday defended the activities of groups such as the National Conservative Political Action Committee (NCPAC), saying that they create "a climate of doubt" about Democrats and are "on balance" a help to the Reagan administration.

"I have a feeling that you have to establish the negatives," Nofziger said. ". . . If they want to go out and beat [Maryland Democratic Sen.] Paul Sarbanes around the head, that's all right with me."

Sarbanes is a 1982 target of NCPAC, along with Sen. Edward M. Kennedy (D-Mass.) and three highly visible Democrats in the House -- Majority Leader James Wright (Tex.), Ways and Means Committee Chairman Dan Rostenkowski (Ill.), and Budget Committee Chairman James R. Jones (Okla.).

Nofziger issued his defense of NCPAC before the same luncheon group of reporters to whom Republican National Chairman Richard Richards last week decried the efforts of such independent expenditure groups, saying they have the potential of creating backlash sympathy and damaging President Reagan.

"They create all kinds of mischief," said Richards, in comparing their fund-raising activities to those of the Committee for the Re-election of the President that led to the Watergate scandal. "They're not responsible to anyone."

The GOP chairman's statement provoked any angry reaction from several of the political action groups that were his target and from some Republican congressmen who objected to Richards' statement that it was more important to see Congress pass the Reagan economic program than to win Republican control of the House in 1982.

Nofziger also was asked whether it was more important to pass the program or win the House. He ducked it, saying, "I'd like to have my cake and eat it, too."

But he appeared to have no real disagreement with Richards on the prospects of defeating Democrats who supported Reagan's economic program.

Sixty-three conservative Democrats, many from the South, are the focus of administration efforts to win Democratic support for the president's budget. Nofziger said that many of these Democrats come from safe districts and that it would be unlikely in any case that Republicans would have much chance of defeating conservative Democrats who voted with Reagan.

The best chance for GOP gains in 1982 will be if the economic program passes and works, said Nofziger.But he said Republicans also had a chance to make gains if the Democrats stop the program and their opposition becomes an issue.

When Nofziger gave a cautious prediction that the odds favored passage of Reagan's budget this week, a reporter asked him if he thought this was because there was a political benefit to the president "being shot and recovering."

"It beats the hell out of being shot and not recovering," Nofziger replied.