Three professional political consultants agreed yesterday that there are flaws in the presidential nomination process. But they opposed regional or time-zone primaries as a solution and warned that attempts to change the system could create new problems, as has happened in the past.

They agreed that people may think the presidential primary season is too long but expressed doubt that this is the principal reason for the relatively low voter turnout rate, which was about 53 percent in the November presidential election.

Low turnout, the consultants said, may be more the result of people doubting their votes have impact or that the candidates and issues are relevant to their concerns.

"It has more to do with efficacy and the effect of their votes," said Patrick Caddell, a pollster and consultant to the presidential campaigns of Democrats George McGovern, Jimmy Carter and Sen. Gary Hart (Colo.). "It has more to do with government than with the length of the political process."

Caddell and Republicans Lee Atwater and Lance Tarrance testified before the Committee on National Elections, a bipartisan panel sponsored by The Center for Strategic and International Studies to study and possibly recommend changes in the electoral process because of a perception that presidential elections are too long, cost too much and attract too few voters. The cochairmen are Robert S. Strauss, a former chairman of the Democratic National Committee and trade ambassador in the Carter administration, and Melvin R. Laird, a former representative from Wisconsin and secretary of defense in the Nixon administration.

"Because of notions we've gotten from civics classes, there is a feeling that all of us should vote; but given the impact of one vote on the system, many people don't feel that it's a rational use of their time," Atwater said.

Tarrance, a pollster based in Houston, said that rush-hour traffic in some cities discourages many voters. He advocated greater use of absentee ballots.

Strauss contended that people are "depressed" and "cynical" about a process that takes so long "and then doesn't give them the choices they think they should have."

Caddell and Atwater rejected shortening the nominating process with regional or time-zone primaries because they would require a lot of money and would favor incumbents and front-runners.

Caddell defended the current system because the early primaries allow unknown candidates the opportunity to campaign person-to-person and make an impact without needing a lot of money.

"Everything we do at the beginning of the process should assure that unknown candidates should have a chance to be heard and emerge," he said.